Tim Burton's Batman, in the final battle when The Joker pulls that gunout of his pants. The thing is longer than he's tall!
Ultraviolet, where the main character has these funny little bracelet things that store her weapons. There's a great scene where, after Violet loads these things with enough weaponry to supply the entire US military, she is scanned by a weapons-check program and it gives up counting the weapons she's carrying.
The Matrix movies. While in the Matrix, Trinity is always dressed in skintight clothing with nowhere to hide a gun, but she can always pull out firearms (and her cell phone) whenever needed. But then again, they're inside the Matrix and as such have access to "magic."
Trinity pulling out weapons
At the beginning of The Matrix, while escaping from the Agents. After falling down some stairs, she pulls two pistols out of nowhere.
In The Matrix Reloaded, she pulls a pistol out of nothingness twice (to menace Persephone and while fighting the albino Rastafarian ghost identical twins), and draws two machine pistols out of hyperspace while fighting the Agent in the power control building.
Trinity pulling out her cell phone
Averted in the first film. Although she pulls out her cell phone several times, she always does it either from a legitimate source (a pocket or a carrying case on her belt) or while she's offscreen.
In The Matrix Reloaded she pulls out her cell phone from nowhere three times: while she's on the motorcycle transport vehicle with the Keymaker, while she's outside the building that controls the backup power supply, and after reaching the 65th floor of that building.
Near the climax of The MonkeesfilmHead, the band is confronted by a posse led by Lord High 'N Low, who's been after them for various reasons throughout the movie. In the half-second cutaway between Davy's shots, while the Monkees' would-be executioners are cocking their rifles, Davy produces a loaded, packed, & primed cannon and wipes out the whole posse. Peter lampshades it less than 5 seconds later.
As mentioned in the introduction, all the Immortals in Highlander have a personal Hammerspace where they keep their swords. It's not hard to believe that Immortals are issued pocket-sized interdimensional trap-doors upon waking up and discovering their immortality. Methos, in particular, managed to hide a particularly long broadsword (an "Ivanhoe" if you want to get picky) in his. And Silas didn't seem to wear coats at all, but managed to favor a battle-axe for his battles. He possibly kept it hidden in his sweater. And Amanda seems to hide her sword in her hair. (She has quite short hair, mind you.)
One notable instance has an immortal attacked while in a spa, and he pulls out a previously unseen sword despite wearing nothing but a towel.
Possibly explained by immortals, who having lived for centuries, have just gotten really good at stashing their weapons in places that we the viewers couldn't have thought of. And if the first movie is any indication, if you're caught without a weapon, you can just grab a metal bar to defend yourself.
Harpo Marx can and does keep anything and everything in his (admittedly large) clothes, including a complete silver tea set, fully fueled welding equipment, live animals, a steaming hot cup of coffee, and once a lighted candle — lighted at both ends. This only counts as Hammerspace from a viewer standpoint, however, because Harpo Marx actually did produce these items from his custom-made coat. It was a gag he developed for use live on stage.
Interestingly, the Looney Tunes (who often employ Hammerspace) were inspired by Harpo's gags, in the same way that Bugs Bunny is modeled on Groucho Marx (and just a dash of Clark Gable)
Mary Poppins's bag, which is shown to store potted plants and lamps, making it a Bag of Holding. One might say the same about Harpo Marx's coat, but that was played more for laughs: you wonder what kind of clown carries a tea set around, less about how he does it. The way that Mary Poppins pulled tall items out of her bag, it's clear that the bag is larger inside than outside.
When the children look in the bag, they see it as empty.
In one scene of Jesus Christ Vampire Hunter, a jeep pulls up by Jesus and a few atheists come out to beat up Jesus. As the scene goes on (and Jesus takes care of each successive wave of nonbelievers), more than thirty atheists end up coming out of that little jeep. Lampshaded when Jesus, on defeating the first wave, throws his hands in the air in an unmistakable "Are you joking?" gesture when the second comes into play.
Rat: *still pulling out swords, then stuttering from all the stuff he pulled out* Aw, man...
Any doubt that the H. P. Lovecraft adaptation The Unnameable is really more of an understated horror comedy is finally dispelled after the film's climax, when the smart guy reaches beneath his thin jacket with one hand and pulls out an oversized book of spells nearly as large as his torso.
Anchorman: The four lead anchormen are walking through San Diego trying to find a suit store. However, that doesn't stop them from pulling iron knuckles, a club, and a HAND GRENADE amongst other things when they encounter a rival news team.
Ron: Brick, where'd you get a hand grenade?
Brick: I don't know.
The Goonies: Data looks pretty normal-sized through most of the movie, until a bad guy gets close and suddenly his jacket puffs out as he punches the guy in the face with a spring-loaded boxing glove on a mechanical arm. In the scenes where it is actually used you can tell that it would've been very noticeable had he been walking around the entire movie with that contraption under his jacket.
A Running Gag in Versus is that the weaselly yakuza seems to have an inexhaustible supply of pistols stuck into the back of his waistband. Whenever he loses a gun, he immediately pulls out another, larger one from the exact same spot.
In Hudson Hawk, one of the villains cuts open the cover of Da Vinci's codex to reveal that the book cover, which was approximately a quarter inch thick, contains a piece of the gold machine reflector which is about the size of a billiard ball.
In The Mask, Jim Carey has an infinite amount of space inside his pockets and an unknown, probably infinite number of things in them.
In the BIONICLE movies, the Toa keep all their supplies, tools, etc. in hammerspace, but it's never made clear where they put them (the animation just shows the objects retracting "into" their solid backside). The novels at least give them the benefit of carrying satchels.
A subtle but cool version in Raising Arizona. As the Biker walks through Unpainted Arizona, a cigar appears in one hand, out of nowhere, and a match in his other, which he strikes on a wall to light the cigar.
In Thor and The Avengers, Loki seems to have access to hammerspace because he often summons his battle outfit (horned helmet and all) out of nowhere, as well as knives to stab Thor with. He's also seen banishing the Casket of Ancient Winters to who-knows-where with a single hand movement after attacking Heimdall with it.
Mallrats: Silent Bob produces several objects from inside his coat, up to and including a fully-inflated blow-up doll.
In Disney's Pinocchio, Jiminy Cricket pulls out a pair of glasses that, while proportionate to his large head, are far too big for his back pocket.
In Top Secret!, Chocolate Mousse pulls a sledgehammer out of nowhere to pulverize a cricket.
DEBS. Presumably where Lucy Diamond carries bulky items (her gun, extra ammo clips, a grenade and the suction cups she used to climb up the wall of the D.E.B.S. house) when she's wearing skin-tight clothing
In Scott Pilgrim vs. The World, Scott frequently makes a hat materialize on his head when a girl comments that his hair is getting shaggy. Ramona also pulls a gigantic hammer out of her purse.
In Robert Rodriguez' Desperado, the bar scene being told by Steve Buschemi has El Mariachi pulling guns out of nowhere, at one point actually brushing his hair back, and producing a shotgun from behind his head.
In Tropic Thunder, Hammerspace is the least disturbing explanation for how Portnoy was able to pull a pistol out of his skimpy undies.
In Tangled, Rapunzel carries Flynn's satchel around for nearly a day in spite of the fact that she had nothing to carry it in, and she was with Flynn the entire time.
Hiccup, in How to Train Your Dragon, has a modest Hammerspace where he keeps a notebook that's too big for a pocket. Moreover, when he puts it away, he just shoves it under his vest in the general direction of his back and lets go.
Jason's backpack in Mystery Team. Somehow he can put together: A hobo outfit, a reporter outfit, THREE gentlemen disguises, THREE Letterman's jackets and A Mexican plumber costume. Duncan has this, to a lesser extent, fitting a slingshot, a "spy camera" and a book of Wacky Facts in his pockets.
Presumably where Richard finds the board to hit Tommy in the face with in Tommy Boy.
Spoofed in the New Zeland film Undead, when a completely naked man pulls a couple of guns from nowhere.
Santa's sack in "The Santa Clause" has a dimension warp that allows it and the bearer to go down chimneys or even stovepipes, and a Smart Hammerspace that produces whatever gift the house's children are due, up to and including a full size kayak.
Iron Man 2: We all love the Mark V suitcase suit, but let's face it, this is where it really comes from. There's no way that suit could fold down into a suitcase-sized package that's light enough to carry in one hand.