Alias: Done to the point of extreme irritation as it's obvious by the end of season two that the writers can't come up with a satisfactory explanation for the prophet Rambaldi but are still going to drag out one tired MacGuffin for the rest of the series.
'Allo 'Allo!: This show is essentially nine seasons loosely tied together with several MacGuffins, in particular, the two paintings: the Fallen Madonna with the Big Boobies by Van Klomp and the Broken Vase with the Big Daisies by Van Gogh. They change hands so many times, usually hidden in sausages, and have been forged constantly, so that it's almost impossible to tell who has them at any one time.
Angel: One episode featured the group going on an Indiana Jones-type search for a mystical sword that is the only thing that can defeat their current foe, The Beast. It was All Just a Dream.
Battlestar Galactica (Reimagined): The remake turns Earth into a MacGuffin Location, uses that fact brilliantly in the third season's mid-season ending, then catches the audience off guard in the series finale. Most of the haunting clues the crew of Galactica have been encountering either fall into place or help promote the idea that the "route to Earth" they have been following is really a series of "predestined convenient encounters." The character of Hera becomes the final MacGuffin needed to find a home planet that turns out to be the real Earth long into its past.
Burn Notice: Subverted Trope: During the last few episodes of Season 4, The List (of the members of the Burned Spies Organization) basically serves as a MacGuffin: people fight over it, but nobody uses it. By the time Season 5 starts, it has been used: the members of the organization are either incarcerated or dead (and we get to see Michael take care of the last two guys). But there's this one guy whose name was never on the list...a rather mild-mannered fellow named Anson Fullerton.
Castle: The eponymous brooch of the episode "The Blue Butterfly". It drives the plot of both the modern-day murder and the murders in the 1940s that drove it to be hidden in the first place. Lots of Shout Outs to "The Maltese Falcon" including the fact that the Blue Butterfly is made of fake diamonds.
The season 4 episode Advanced Documentary Filmmaking, the episode is building up to a visit by a psychological research institute, appropriately titled the "MacGuffin Institute".
Dinosaurs: One unaired episode, "Scent of a Reptile", revolves around Charlene getting her "scent", which will attract one male dinosaur and one male only, who will be her mate for life. When she realises that her destined mate is a slobbish janitor, her grandmother tells her the only way to change her scent is with a very rare flower found on the other side of the world - the MacGuffin Lily.
The two-part first season episode "Chicago Holiday" features a matchbook that supposedly will give the owner control of the entire Chicago west side (whatever that means). The list is passed from hand to hand, but we never learn what is actually written on it, nor is it really important except to further the plot. There is also a hotel cleaning woman named "Mrs. MacGuffin", an In/Out Board that shows Mac Guff as "In", and a store security guard "Niffug, C. M.", whose name tag we conveniently see in a mirror, all obvious Shout Outs to Hitchcock.
As far as the utility and importance of the matchbook, it's got the names and addresses of every dealer and operator on the west side; he who holds the matchbook has power over all of them, a cut of their profits, etc.
The titular team is looking for the Greatest Treasure In The Universe. Said treasure was what their leader, Captain Marvelous, and his former team, The Red Pirates, were looking for before one of their own decided to sell them out to The Zangyack so he can get the treasure for himself.
Subverted Trope in that the Greatest Treasure actually does turn out to have a purpose (it can remake reality) but comes with a heavy price (using it will also Ret Gone all of the Super Sentai), and the Gokaiger have to decide whether or not to use it. They end up destroying it and doing things the hard way.
Legends of the Hidden Temple: This Nickelodeon game show is one of the most literal applications of this trope. Each episode features a historical and/or mythological artifact that is eventually searched for and collected by the contestants. The actual nature of the item is completely unimportant outside of the trivia round, and in fact the item can be, and is, replaced with something else in each episode. The show itself is only concerned with the collection of said item.
LOST: The entirety of the show is an exercise in MacGuffin spotting.
Maddigan's Quest: After various characters spend most of the series either chasing or protecting Eden's talisman, it's revealed as one of these, and in the second-last episode it turns out that the real 'talisman' is Jewel.
The Man from U.N.C.L.E.: The second half of the third season was especially MacGuffin filled: e.g., the stolen U.N.C.L.E. codes in "The It's All Greek to Me Affair", the explosive hula doll in "The Hula Doll Affair", the THRUSH historian's diaries in "The Pieces of Fate Affair", the Project Quasimodo filmclip in "The Matterhorn Affair", and the dress with the THRUSH coded pattern in "The Hot Number Affair" (Season 03, Episodes 21-25 inclusive).
The Mighty Morphin era includes a sword to transfer the powers of the original Red, Yellow & Black Rangers to their replacements (Future power transfers with later powers just featured the powers being handed over).
The Zeo Crystal subverts this as it was introduced in a 3 parter prior to the storyline in which the Rangers sought it out. Furthermore, Power Rangers Zeo would see the Crystal as the source of the Rangers' new powers.
The presence of so much technology and useful spells that served as Mac Guffins led Linkara to jokingly call the Zeo Crystal "The MacGuffin Crystal" in his History of Power Rangers series. However, it's a deliberate lampshade on the subversion.
Season 2 has the characters chasing a MacGuffin all season: Charles Westmoreland's money. It briefly ends up in the hands of T-Bag and Bellick, but aside from an insignificant amount being spent, it only serves to move the plot along. Many things happen because of it, but it ends up as nobody's prize.
Season 4 also has a MacGuffin in the form of Scylla, the company's "Little Black Book." The first half of the season has the team chasing the Plot Coupon known as "cards" to unlock Scylla, but then it's stolen and everyone spends the rest of the season chasing it. Somewhere late in S4 Michael figures out that Scylla actually contains the secret to super-efficient solar power (or something), but it really doesn't matter to the plot. The point is that if they get Scylla, they can destroy The Company, and if they don't, they all go back to prison.
The Prisoner: Number Six's reason for resigning. We never find out what it was; all that's important is Number Six has something the bad guys want, and most of the plots (at least in the first half of the series) deal with their efforts to make him give it up.
Grace, the woman who helped Danny, has one as well, and it seems capable of restoring power (in a limited area, at least). Grace and at least one other party also have a primitive (early 1980's level) computer with acoustic modem capability—implying telephone service as well as electricity—and appear to be coordinating some larger agenda.
As of episode 5, Rachel has revealed the existence of 12 pendants. Three have been accounted for, and the whereabouts of the remaining nine have yet to be revealed.
To be true, we have seen three of them and the action of a fourth (the one used by Grace's correspondent.
Episode 8's map shows seven in the former borders of the USA. Presumably the other five are either "dead" or are in other places besides North America.
Episode 9 reveals that the pendant has an approximate range of 9-10 feet when active. They can apparently be activated if you touch the flash drive part a particular way.
Episode 12: Rachel removes the flash drives from two pendants and drops them in tubs of chemicals to destroy them. This might help explain the other five missing pendants, except it's pretty strongly implied they can only be tracked when active anyway - except when Randall's remotely pinging them.
After Danny's death in "The Stand", the episode ends with Rachel cutting a small capsule out of his side. And it's blinking. Hmm...
Robin Hood: In one episode, a Celtic necklace is taken from a young peasant girl by Guy of Gisborne in order to give to Marian as a courtship present. When she discovers its origin, she gives it to Robin to return to the girl. The necklace exchanges hands several times throughout the course of the episode (eight characters in all get their chance to steal, find, return or give it away) and its whereabouts finally lead to Marian being forced to agree with marriage to Guy.
Smallville: The show loved this trope. Almost every season would feature at least one object—often of Kryptonian origin—that various characters would be jockeying for control of, due to the perception that it would either grant them power or help them solve some mystery. Season 4's plot was especially centered around this trope, as Lex, Lionel, Genevieve Teague, Jason Teague, Lana, Lana's undead witch ancestor Countess Margaret Isobel Thoreaux, Dr. Swann's foundation, and even a rogue unit of Chinese soldiers all start plotting and feuding with each other and tripping all over themselves to track down the Stones of Power, which combine to form the Fortress of Solitude. Clark is reluctant to jump into the middle of this, as his life now has some semblance of normalcy for once, but circumstances and Jor-El essentially force him to hunt down the Stones himself, because—in Jor-El's words—if any of these factions unite the Stones before he does, they could very well be overwhelmed by the temptation to misuse the Fortress's power. Jor-El fears that this would lead to The End of the World as We Know It.
Stargate SG-1: It seems that every fifth episode involved chasing some alien technology MacGuffin that is never seen or heard of again.
The Iconian gateway (and the Jem'hadar rebels holding it) in "To the Death." The plot is really an episode to showcase the culture of the Jem'hadar and how different these Proud Warrior Race Guys are from even Klingons. We never get any characterization for the rebels and the gateway isn't mentioned again.
A few episodes have cargoes of "self-sealing stembolts", whose sole function is seemingly to get sold for more than they're actually worth.
Parodied in "Improbable Cause". Just before Odo and Garak go on a dangerous journey, Bashir, who's spent three years trying to work out if Garak is a spy or not, asks Garak if there's anything he can do for him while he's away. Garak looks around furtively to see if they're alone and then anxiously tells Bashir that if he's not back within 3 days, to go into his quarters and locate a datarod that's hidden behind a false panel. This sounds like the set up to the usual sort of plot where the good guys will later get out of danger by bargaining the fate of some important piece of information that could fall into the wrong hands if they die. And then Garak tells the wide-eyed Bashir to eat the rod. At that point, Bashir (and the audience) realises Garak's just cracking a joke at Bashir's expense.
The music box, which drives the arc after the first six episodes, and serves no purpose other than the fact that Fowler wants it.
Subverted Trope. It seemed like one at first, but has since been revealed to contain information (through music) for a fractal pattern that lead them to the real bad guy, and which has a purpose that they will also reveal. Certainly, it still didn't need to necessarily be a music box, but it is no longer just any object, but has specific information with a purpose that is being revealed.