Nearly every bulkhead in any starship or other vehicle designed by Leiji Matsumoto will be covered in an insane array of electronic instruments, usually glowing, circular, and inset into said bulkhead. They're affectionately known as Matsumoto Gauges, rhyming with Matsumoto Leiji.
Jack Kirby covered everything in Cow Tools. He was incapable of drawing a simple box; every device had innumerable chrome tubes, knobs, discs, and zigzags to no apparent purpose. Guess he wanted his machines to complement the dots they generated.
Parodies like Twisted Toyfare Theater have a ball with this. "Help me lift this giant piece of Kirby-esque machinery!"
Although Gary Larson claims that the reaction surrounding the Trope Namer will haunt him until the day he dies, it actually generated a lot of positive publicity for The Far Side and may even have boosted its circulation.
There were a few other Far Side cartoons involving these. In one, gangsters torturing a hostage bring out what they call "Mr. Thingy," which looks like a fishing rod attached to a bicycle horn with a carrot on the string. In another, "Harold finds his purpose," a man digging around the couch finds a ball with springs coming off of it, including one with a duck's head attached. Larson has stated that after the controversy over "Cow Tools," he was afraid people would overanalyze these ones.
Bag Enders episode "A Shortcut to Whitby" features the "long bent thing with sort of a knob on the end" (inspired by a similar item on an episode of The Goon Show). The Fellowship lose it before they find out what it does, and the people who find it by the side of the road don't know either.
In All's Fine that Ends Okay, Kiku is sent a mysterious object which does absolutely nothing but turn Hercules and Sadiq - and only them - invisible. After that arc is resolved, it doesn't really do anything else, and no one actually figures out what it is or how it works.
There is a scene in Tim Burton's Sleepy Hollow where Ichabod is doing an autopsy; there is a tray full of strange, complex looking surgical tools next to him. What they're for and how they work is anybody's guess, but they do resemble some of the more esoteric medical devices from the era.
Tia Dalma's hut in Pirates of the Caribbean: Dead Mans Chest is stuffed full of voodoo-related Cow Tools. There's so many that two Chekhovs Guns among them (Barbossa's boots and Calypso's locket) are easily missed.
Also a subversion in Pirates of the Caribbean: The Curse of the Black Pearl: the scene where Norrington reveals Jack Sparrow to be a pirate, he goes through Jack's seemingly only earthly possessions, which include a pistol with only one shot, a compass that doesn't point north, and a relatively normal sword. It seems to be a rather pathetic assortment of Cow Tools, however, over the course of the series, all of them end up being used. Ironically, the only item that ostensibly seemed to be of any practical use, the sword, was the least relevant to the series overall. The pistol and the compass prove to be highly significant Chekhov's guns in the first movie, and the sequels, respectively.
Dr. Orin Scrivello's rather painful-looking dentist's tools in Little Shop of Horrors certainly qualify for this.
They made a reappearance in Tim Burton's Batman as the plastic surgeon's equipment, too. And were lampshaded with his forlorn "You see what I have to work with..." That was an Actor Allusion, as Jack Nicholson appeared in the original Little Shop.
The painful-looking information retrieval implements in Brazil are surely related.
Tony Stark's machine shop in Iron Man exemplifies this trope. At some points it seems like there's more stuff in there than you could possibly logically need to build a super suit, regardless of how complex that might be. Things like a pillar drill are necessary for any well-funded chronic tinkerer.
Famously lampshaded in Buckaroo Banzai, where the labs are full of Cow Tools. "What's that watermelon doing there?" [in a hydraulic press of some sort]. "I'll explain later."
Itself lampshaded in an early BattleTech novel, with the setup being recreated by a clear Captain Ersatz of Dr. Banzai. (It's later revealed to be simply an object lesson to any idle curious who disturb the setup — mess with the watermelon and an alarm goes off, complete with a message about the hazards of interfering with things you do not understand. This actually becomes useful during a raid on the institute when a stray laser shot vaporizes the watermelon and the alarm distracts an armed intruder just long enough to be dealt with.
In universe, it was an experiment by the Banzai Institute on how to treat food so as to be easily airdropped into famine-starved countries without damaging the food (by making it bounce or resist crushing; the experiment was abandoned when someone realized that any food that could survive an airdrop would be too tough to eat). Behind The Scenes, it was explicitly an attempt at Getting Crap Past the Radar on a production which had been besieged by meaningless Executive Meddling (including a screaming Flame War over whether Buckaroo would be allowed to wear red-framed glasses onscreen). The director and staff put the watermelon in, with no attempt to explain it, to see if they had finally fatigued the executives' supervision.
In David Cronenberg's Dead Ringers, the less mentally stable of the twin gynecologists has invented a ghastly-looking array of bizarre surgical instruments, which we see in a brief, rather chilling scene.
In Ghostbusters, Venkman enters Dana's flat operating a strange device with a long tube and a rubber bulb that appears to pump air through the tube. When she asks what it does, he replies vaguely "It's... technical. One of our little toys." (Actually the device does have a purpose, Venkman just has no idea what he's doing.)
The commentary reveals that Bill Murray was given a selection of Cow Tools to choose from, and thought that one was the funniest.
That thing is also never used, seen, or even mentioned again.
Monty Python's The Meaning of Life. "This is the machine that goes 'Ping'. It tells us that your baby is still alive." Somehow, it does so without being hooked up to the expectant mother.
Likewise from the same scene, The Most Expensive Machine in the Hospital, whose purpose is apparently...to be The Most Expensive Machine in the Hospital,
The interior of the Seaview in Voyage to the Bottom of the Sea and its TV follow-up is full of random flashing lights, switches, screens, boxes, and wires that don't serve any apparent purpose. The lights are so prominent a character actually says "it's always Christmas on a submarine."
The film The Shape of Things to Come, fondly remembered by B-movie fans as "Blinky Blinky" due to the tons of weird machines with blinking lights in almost every scene.
Unexplained bits of tech are sometimes thrown in as a joke in Q's laboratory in James Bond films.
Event Horizon had a medic named CJ, who was carrying a vast array of not-very-useful tools on his vest. His actor initially wanted the character to wear the items to aid in character design, but quickly found them cumbersome and irritating. No medic or paramedic would want such a strange rig; there are much more elegant solutions to keeping your gear handy and much more important gear to have within immediate reach.
In Predator, the Predator is injured by Mac during the More Dakka scene, and uses a variety of alien Cow Tools to patch the wound. According to the director, these are based off of actual veterinary tools.
Crow T. Robot: Increase the Flash Gordon noise and put more science stuff around!
Spider-Man 3. What is that machine supposed to do? What was supposed to happen to the sand?
Subverted in Gran Torino. Walt's garage is filled with hundreds of tools, and Thao points to several of them at random and challenges Walt to name them. Walt knows what each one is called and what it's used for.
Subverted in Total Recall (1990). Quaid takes an unfamiliar-looking handgun-like device from the suitcase he was given earlier. He looks at it, then puts it next to his pistol. A short time later, we find out that it's a device for removing tracking chips implanted in one's head.
In Harry Potter, Voldemort hid a horcrux in the Room of Requirement, where for centuries students have been storing total junk. When he hid it, a bunch of other random stuff was there, and it's speculated whether Voldemort thought that was created by magic, or whatever, because he claimed that he was the first to find it.
All the insanely weird stuff in the Department of Mysteries.
Dumbledore's office has a variety of inventions, which he can use whenever, but which are beyond the realm of the audience's understanding.
Also lampshaded a few times: Archchancellor Ridcully, in a pinch and pressed for time, manages to perform the ominous Rite of Ash-Kente to summon and bind Death with two candles, an egg and some string. Wizards like all the ornamentation, though; and besides, the more difficult and complex the ritual, the less likely that some random idiot who doesn't really know what he's doing will try it.
The Department of NecromancyPost-Mortem Communications is full of dribbly candles, cobwebs, skeletons and assorted Cow Tools, because if a spirit is going to make the effort of piercing the veil and returning to the living world, a wizard ought to make the effort to see that things look right.
Also, nobody knows what most of the stuff hooked up to Hex actually does, including Ponder Stibbons and Adrian Turnipseed, who built the thing in the first place.
Although this is also because Hex has a habit of adding things all by itself!
The addition of Anoia, goddess of things that get stuck in drawers, to the Discworld pantheon has provided excuses for many kitchenware Cow Tools to have their inexplicable and/or useless presence in everyone's cupboards lampshaded.
The "offog" from Eric Frank Russells' science fiction short story "Allamagoosa." Many purposes, as well as descriptions, are put forward for this essential item of a starship's inventory....unfortunately, all of them are wrong. The ship is being inspected by Admiral Beancounter, so the pressing concern for most of the story is not what it actually is, but that they have to have one.
Subverted in the Niven and Pournelle work The Mote in God's Eye when the Moties present the humans with a room filled with what appear to be Cow Tools but are not. The tool room is actually an "IQ" test of sorts. The humans are expected to determine the flaw in each tool which renders it useless. Naturally the person who figures this out is the ship's engineer.
In The Voyage of the Dawn Treader, we see some stuff like this in Coriakin's lair. The most prominent example is the Bearded Glass, which is... well... a mirror with a beard attached. When someone passes, their reflected face looks like that of a bearded weirdo jumping out of the shadows. It may serve some purpose, or Coriakin may have simply put it there to prank what few visitors he gets. Even C. S. Lewis says he doesn't know what it's for.
Live Action TV
Every Mad Scientist has to have a plasma lamp, to evidently show his technological prowess, regardless of the fact that every Spencer Gifts and Circuit City in the world sells them for about $25 each. Also, some piece of machinery topped with a "Jacob's ladder" spark gap, plus flasks of colored (optionally foaming) liquid, as all mad scientists apparently dabble in chemistry by default.
A standard gag on many "bad movie" review sites: "Beakers of strangely colored fluids? There must be SCIENCE going on here!"
Many of the tubes, conduits, and access panels of the dressing the original Star Trek sets were labeled with the cryptic acronym GNDN to remind the stage crew that this or that prop machinery was merely for show and that it "Goes Nowhere, Does Nothing".
One great example that was used as a recurring plot device is the self sealing stem bolts in several episodes of Deep Space Nine. It is pretty much a case of lampshading, as Jake and Nog try to make some money out of a wrong delivery that was about to land in the garbage, but only end up with more useless junk until they finally get their hands on a shipment of self sealing stem bolts. As Jake points out, neither of them has any idea what they are used for. Later on in the series the self sealing stem bolts make a few reappearances. Every single time, there seems to be someone who knows what they're for, but not any of the characters on screen.
For the Star Trek mess hall, the set dressers went out to various shops and bought a bunch of unusual salt and pepper shakers. However, they were all considered too confusing for the viewer and normal looking ones were used. They got put to good use however, as they were put in the Sick Bay as futuristic medical devices.
Whenever a Star Trek crew member removes a panel from a wall, they're always filled with futuristic circuitry and other such phlebotinum. At one point, they were overused so much in episodes that set decorator Jim Mees had to politely remind the writing staff that he had to build each and every panel interior, and that they cost about $1000 each. They became known internally as "Mees panels".
Lampshaded by a joke in Airplane II, where William Shatner's character is annoyed by a big fancy machine that doesn't actually do anything. For bonus points it's the same blinking tube device from Star Trek II, and It also appears in the Alien Nation movie and elsewhere. It's a popular prop.
Sam's lab in Stargate SG-1 includes some things that are supposedly alien technology she's analyzing. Some of it has an obvious purpose, some of it is from previous episodes, but most of it is completely random.
Turned around in one episode where an alien, who's lost his memory, is working on a TV show and one of his actual alien devices is being used as a Cow Tools prop in the show.
Discussed in the DVD commentary for the Doctor Who serial The Caves of Androzani, when a man gets his head shoved in between two parts of a futuristic machine thing which immediately starts glowing. The serial's director notes that "we don't know what it does, but it's killing him".
From the newer episode, "Blink": "Tracked you down with this. This is my timey-wimey detector. Goes ding when there's stuff. Also, it can boil an egg at 30 paces. Whether you want it to or not, actually, so I've learned to stay away from hens. It's not pretty when they blow."
More generally, the TARDIS. It's always had way more buttons, knobs, levers, and random knickknacks than they ever actually use or have any kind of meaning for, but in recent years, the main console has gone so far as to include illogically placed bits and pieces of just about every kind of household objects imaginable, including for instance most of a typewriter with no ribbon or paper.
The Adventure Game series had the interesting but unenviable task of actually explaining what everything on the TARDIS console does. They should get a medal.
"Broken. Broken. Hair dryer..." One has to wonder what the others would have done if they'd been working (Cow Weapons?).
Subverted in "The Family of Blood". John Smith (the Doctor as an ordinary human) enters the Family's spaceship and clumsily struggles with some seemingly meaningless controls. The Family considers him a harmless buffoon. The subversion is that this was actually the Doctor himself all along, and he was setting the ship to self-destruct.
In Babylon 5, maintenance extras regularly walk around pointing vaguely cleaner-like or metal-detector-like gadgets at the floor. In A View From The Gallery two of them even speculate on what they are for.
Lampshaded, used strait and subverted in the laboratory where Galina Sergeivna works in the russian comedy "Papas Daughters." Often they will be doing serious work, sometimes brewing tea or vodka. but most of the time it is just bubbling water colors.
Mythbusters has the real special effects studio M-5 as their base of operations, with all sorts of equipment that comes in handy for testing myths. The shop itself is constantly cluttered with devices, tools and a wall of cubby shelves with interesting labels that are more or less accurate ("Raw Meat" is one in particular that we hope is less). At one point trying to do a scale test, they needed an action figure and after a minute Jamie produced one from one of the cubbies. At other points devices from past and upcoming episodes can be seen in the background. Props from other films the studio has worked on are also around.
The "Raw Meat" label is actually one of a few that the producers insisted be put around to make the space more. . . cow tooly.
In The Red Green Show, junk-store owner Dalton Humphrey finds an odd looking device in his garage, and has to resist the male urge to keep it until he figures out what it's for.
Lots of the items stocked at Obscura, the weird antiques shop on Oddities, consists of gadgets that probably qualified as Cow Tools even when they were brand-new, and certainly do now that they're long-obsolete.
The Whose Line Is It Anyway? game "Props": the performers are handed a Cow Tool, and they invent several possible uses for it.
In the episode "Hollywood Babylon" of Supernatural, the Concept Art of the monster from Hell Hazers II: The Reckoning shows him holding a flaming fraternity paddle with chainsaw blades around it. They never explain the purpose of this implement.
"The Marvellous Toy" written by Tom Paxton and most famously performed by Peter Paul And Mary is about a Cow Tool toy:
It went "Zip!" when it moved And "Pop!" when it stopped And "Whirr!" when it stood still. I never knew just what it was And I guess I never will.
The eponymous "thing" (represented by a "thump, thump-thump" sound in the lyrics) in bandleader Phil Harris's novelty song "The Thing" may qualify for this trope. The singer never describes the "thing"; the listener only knows that it's something nobody wants to look at, let alone deal with.
I picked it up and ran to town as happy as a king I took it to a guy I knew who'd buy most anything But this is what he hollered at me as I walked in his shop: "Ohhhhh, get out of here with that [thump thump-thump] Before I call a cop!"
As mentioned above, in The Goon Show episode "The International Christmas Pudding", Seagoon's collection of vital equipment included a "long bent thing with a sort of lump on the end." The episode "Wings over Dagenham" also had a throwaway gag about "Long twisted things with holes in the end" being used as currency.
The 2E D&D supplement Arms & Equipment Guide included a description of tinker gnome "armor", a full suit of leather with so many assorted Cow Toolsaffixed to its every surface that it functioned like studded leather armor.
The alien bases in the X-COM games are stuffed with these. Seizing said bases (or sufficiently equipped alien craft) even nets you research angles revolving around the insidious uses of the devices, (useless as they may be to humans). Heck, some of them are even literal Cow Tools (either for use on cows, or made out of cows).
Both Dr. Kleiner's and Dr. Vance's labs in Half-Life 2. The former has a working mini-teleporter among the other seemingly random devices. The latter has a strange machine that sends visible rays through an object (possibly another Xen sample) which can be rotated with the controls on the panel, although nothing really happens. This is made even more strange by the fact that, during the lengthy break in action where you're expected to explore the lab, Dr. Vance specifically invites you to have a look at it, as if it were something important.
It's a miniature of the "Resonance Cascade" effect from the first game. Since Gordon was actually in the test chamber when it happened, it makes sense to expect him to be interested.
Fallout 3's Mothership Zeta. The shelves of the interior corridors of the titular ship from Fallout 3's final expansion are adorned with all varieties of Cow Tools.
The whole game really does this. There's tons of junk items lying around that serve no real purpose other than atmosphere. (Of course, if you're a good player, you'll quickly learn to pick out the Vendor Trash among them)
In The Official Book Of King's Quest, the hints section for the first game notes that the rusted pump and axe outside the woodcutter's cottage were "put there by evil animators trying to drive you crazy figuring out what to do with them".
In King's Quest V: Absence Makes The Heart Go Yonder! there is a strange astronomical-looking device outside Crispin's house, which is one of the first things in the game that you're likely to see. It serves no purpose whatsoever, and your annoying sidekick warns you not to touch it.
Toyed with in King's Quest VI: Heir Today, Gone Tomorrow. The Pawn Shop has dozens of bizarre items on the shelves that you can look at but not buy. If you look at them, the narration will identify things like "whale tongue climbing gear" and a "bridge repair kit". The joke is that these are all things which would have been immensely useful in earlier games but are completely useless in this one.
The Myst series and its sequels has plenty of these. Most of the time you can puzzle out the various tools that Atrus and Gehn have lying around, but many of the other things are a mystery. On the other hand, sometimes a seemingly-innocuous doodad will prove to be a vital clue.
The Geneforge series is littered with Vendor Trash generically described as "Shaper Equipment" and exotic looking props, some of which can be interacted with a "that's not important" Hand Wave. Presumably the characters know what they are; whether the player is ever informed draws the line between Cow Tools and MacGuffin.
Sigil in Planescape: Torment is jam-packed with odd-looking buildings, twisted sculptures, and bizarre devices that you have no idea what they're for. You can click on them to get a description. Many of them will then say "You have no idea what this is for."
On the other hand, there is a shop filled with bizarrely-described items, almost all of which turn out to be crucial plot tokens. (Just not the baby oil made from real babies.)
Lots of old platformers (but especially Mega Man) have many, many levels in labs and power-stations and so on; the walls are always covered in computer-buttons, giant gears, and in general, anything science-y looking, since how else would you know you were in the future?
Many tech-y places in Pokémon games will have machines and computers with various descriptions. Sort of justified since the player character is usually 10 and might just not know. Rarely, an important gadget or message will be hidden in one.
It's a lot of words and numbers that don't make any sense...
Lights in different colors are flashing on and off.
I wonder what this machine is? Better not touch it!
The magic shops in the Quest for Glory games play with this constantly. For instance: In Quest for Glory II: Trial by Fire, Keapon Laffin's shop holds a scale model of the USS Enterprise, a rotary fan, xray specs (useful for one scene and only one scene).
This actually becomes an In-Universe example of Cow Tools since the town itself is implied to be sapient and out to make you suffer. That's right, Silent Hill itself is planting props to scare the hell out of those trapped inside it, and it's doing one hell of a good job.
The Glider PRO CD "SpacePods" even has one room titled "Function Unknown." Most of the supposedly alien furniture is really ordinary furniture objects that have been bizarrely arranged or graphically glitched.
Lord only knows what half the stuff in Dottore's lab do; he's got a jukebox that plays Wagner to help him think, but that's about it. The storage-boxes in the background when Columbina goes to the storage basement are full out shout-outs to famous technobabble, including turbo-encabulators, blinkenlights, and vgrep scanners.
In The Mansion of E, the eponymous structure has numerous examples of these scattered about.
Danny Phantom where a couple of Jack Fenton's invented ghost weaponry are so oddly shaped or out of place that one wonders what the blinding hell they do exactly. His wife pointed out a similar reason in one episode.
Dexter's Laboratory is the king of this trope, featuring an enormous variety of technological inventions in Dexter's lab that are never explained and their use is never revealed. Many times, Dexter will be seen working on a particular gizmo (almost always by simply tweaking it with a wrench) that very, very rarely has any importance in the plot.
Lampshaded by one commercial for the show, that showed a loop of Dexter using his wrench on said gizmo for several seconds before the narrator says "Y'know, eventually, he's got to overtighten that thing."
Another good example is Merlin's cottage in Disney's The Sword in the Stone. It's full of little gizmos and gadgets Merlin is said to have acquired from the future. Some, like a globe, a model of the solar system, and vehicles like trains and biplanes, can be recognized. The rest are simply eye candy.
Or maybe they are from so far in the future our present hasn't caught up to them yet and we won't know what they do until it does.
Basil of Baker Street has a lot of these lying around his flat in The Great Mouse Detective. Most have a fairly easily discernible purpose, though - for example devices for producing cigarette ash and footprints for analysis.
In Batman Beyond: Return of the Joker, during the flashback to the Joker's death, there's a shot of some innocent junk lying around (a toilet plunger, for example). Word of God says originally Joker's tray was originally going to have bloody surgical instruments but the execs put their foot down.
In "Homer vs. Patty and Selma" Homer has a dream where he's rich and successful after inventing some kind of device. Both Homer and the viewers are left equally clueless as to what the device is or what it does.
Adventure Time: In Castle Lemongrab, Finn and Jake find a hallway connecting several small, identical rooms, each one holding nothing but a pedestal with a catcher's mitt on top. Storyboard artist Thomas Herpich said in his blog that these rooms were simply meant to be "weird and mysterious", but later was explained to be Lemongrab's disturbingly inept attempt at trying to understand normal society.
Any place where tools, spare parts or electronic equipment is stored will have a few of these. Slightly downplayed in that all of it clearly had a vital function at some point, but it hasn't been needed in quite some time and chances are nobody can quite recall what it was originally used for.
Any factory floor, automotive garage, or maintenance shop is this to the uninformed/untrained visitor.
Subverted: Modular Synthesizers◊ almost always look like old pretend sci-fi tech, but in fact every knob, button and blinking light serve a purpose.
The vast array of tools found in a dentist's office.
Unfortunately, the Steampunk subculture's costuming element is almost completely dominated by this trope; a fact which this song laments. It is a particularly egregious tragedy in Steampunk's case, because of the fact that, where the Victorians were concerned, the entire reason why things looked good, was because said things were a product of genuinely superior and more careful craftmanship. The Steampunk scenesters have essentially turned that ethic entirely on its head, with predictably distressing results.