King of the Comics' improbable weapon users is Bullseye. Starting from probable to improbable, billy clubs, javelins, sais, shuriken, broken glass shards, rocks, flash lights, dolls, apples, gumballs, teeth, toothpicks, playing cards, seaweed, and to top it off.... A paper airplane knocked someone out. As he said to Elektra, "You're good, but me? I'm magic!"
To quote one of his funniest uses of this abilities to date in the mainstream universe "So which eye, left or right?" "Which one is harder?" "From the distance, with the wind factor, using a yap dog? Left eye." And lo, the yap dog did indeed hit the left eye, yapping the entire time in flight.
Bullseye: They have me on stool softeners and liquid food because they're afraid that if I have a solid bowel movement I'd kill someone with it. And I would, too."
Gambit has the ability to turn any inanimate object he touches into a bomb. He has a preference for playing cards but has alternatively used small change, his staff (which is at times Adamantium and thus isn't completely destroyed), poker chips, sand, credit cards, billiard balls, a bus, and in a particularly vicious example, someone's moustache.
Ultimate Gambit uses this trope to his advantage in his first appearance (whether intentionally or not) to such an extent that his foe assumes that Gambit was powerless when not using his "trick cards". He was quite wrong.
The best example was Gambit charging the metal in Wolverine's skull.
Spitting his gum into the X-cutioner's face was pretty good too.
The Gambit in Age of Apocalypse killed Wolverine, not that Wolverine, by sticking a large rock down his pants, charging it, and then pushing him off a cliff. Boom.
Gambit's power works by inducing objects with kinetic energy; this not only makes these objects explode but also allows them to be propelled like a missile.
"Don't make me throw this pancake at you!"
Ultimate Hawkeye used straightened paper clips, to say nothing of the time he murdered several men by flicking his fingernails at them.
Among villains, The Joker has killed with acid-squirting flowers, super-juiced joybuzzers, BANG Flag Guns where the flag is also a deadly spear, and many others.
In his '90s run on X-Factor, Peter David introduced Professor Rick Chalker, who surgically transformed himself into Number One Fan by having his hands replaced with giant, razor-sharp fan blades. Ironically not the sharpest tool in the drawer, he realized too late that he was trapped in his impenetrable lab by his lack of hands, and out of frustration, slapped himself in the forehead (with gruesome results). He was brought back to life along with his relatives Vic (who electrocuted himself while testing his super exoskeleton in the rain) and Dick, but their collective ineptitude quickly killed them for good.
The Green Goblin and his successors are known to use plastic ghosts alongside their other weapons.
Hush, from Batman fame, was a standard gunslinger in his original appearance, but turned evil doctor in a couple later, throwing scalpels, syringes, and having Catwoman in an iron lung.
Night Thrasher frequently used a bulletproof skateboard as a weapon in his early days. It even had a "snikt" retractable blade!
A crossbow-taser was a favorite of Night Thrasher's step brother Bandit. Even more weird in that his own body generated the electricity for it.
Blade's Wordsword. Instead of using spell books how they were intended, Blade tore out their pages and paper mached himself a sword out of them. In his own words: "Great against demons, not so great in the rain."
Though it's somewhat understandable, the last time he tried to cast a spell he got possessed.
CrossGen comics had a few of these. "Now, give me what I want or I'll show you what else I can do with furniture."
Most Silver Age super villains had a theme centered around an improbable weapon or odd piece of technology.
Spider-Man villain Typeface was a signsmith who used big letters as weapons.
Spider-Man counts as well. His webshooters aren't typically thought of as weapons, but just wait until he wraps you up in a coccoon of webbing. Or snags you with one end of a webline and yanks really hard. Or hits you with another heavy object or person he's snagged with a webline. Or knocks you unconscious with a high-velocity glob of webbing.
Or catches you as you plummet from the George Washington Bridge! Wait...OH GOD!
Spider-Man has an enemy called Boomerang who is a former baseball pitcher who has skills similar to Bullseye's (to a much lesser degree, of course) and can potentially turn anything he can throw into a weapon. This is sort of a subversion, however, because as his name suggests, he usually uses boomerangs, which are real weapons. (However, in the Deadly Foes of Spider-Man mini-series, he makes good of this ability in two attempts - one failed, and one successful - to escape from jail, using things like a watch, a stapler, and even coins as thrown weapons.)
He killed everyone in a taco restaurant- with a spork.
Salad tongs, flaming corn dog stick, raw potato, boiled potato, a Bolt candy dispenser, a packet of ramen noodles, Mexican candy, most recently a walrus... Hell, the man once stabbed someone with hot mashed potatoes. Yes, he took a bow for it.
One The Far Side comic featured the Dobie-O-Matic, a weapon that launched dobermans.
Obelix has been known to use a menhir as a weapon.
X-Men's Colossus has been known to use the Fastball Special, which is throwing a most unusual thrown weapon: Wolverine. He's not the only strongman in Marvel to have a teammate who occasionally acts as a thrown weapon.
In a Peanuts strip, Peppermint Patty hires Snoopy to be a watchdog, and Charlie Brown suggests he bring a weapon; Snoopy says, "That's a good idea. I'll bring the most dangerous weapon known to man!" He brings a hockey stick. (When he gets to her house, she tells him to get rid of it, saying, "I could get mugged while you're in the penalty box!")
Also, Linus has been shown using his Security Blanket as a bullwhip, with enough strength to knock people out and enough accuracy to hit a tossed coin. There's a good reason nobody laughs at him for that blanket...