Back to the Future Part III
While the futuristic second entry in the series would have been a better fit for 3-D, the third BTTF still has the flying DeLorean and hoverboard, as well as a runaway train and a whole bunch of Native Americans on horseback, firing arrows at Michael J. Fox. We'll take it!

Rocky III
The only way Sylvester Stallone fighting Hulk Hogan and Mr. T could be any more awesome would be if it happened in the majesty of three dimensions. We'd love to see Rocky's punches, Thunderlips' mustache and Clubber Lang's mohawk leaping off the screen at us.

The Godfather III
Okay, papal banking scandals don't sound that appealing in 3-D, but what about a guy getting stabbed in the throat with his own glasses? Gore-tastic.

Star Trek III: The Search for Spock
Young Spock's face stretching could be a cool 3-D effect, if done right, but we'd be more interested in the William Shatner-Christopher Lloyd fight on the surface of the crumbling planet Genesis. Also? Exploding Enterprise. We want those Klingon bodies to land in our laps!

Mission: Impossible III
Tom Cruise running in 3-D for two hours straight could prop up the global economy for several decades.

Star Wars: Episode III - Revenge of the Sith
If rendered in 3-D, the opening armada battle sequence alone would cause projectors to melt and brains to explode. But if we survived that, the climactic lightsaber duel in a lava field would be pretty darn neat, as would Yoda and Palpatine's Senatorial seat-throwing fight.

Superman III
Clark Kent vs. Superman in a junkyard? Visually awesome. Richard Pryor skiing off of a skyscraper? Not so awesome.

The Karate Kid Part III
A lot of training montages may not do much for us, but a mid-movie rappelling sequence could add some much-needed vertigo to an otherwise lackluster 3-D movie.

Beethoven's 3rd
Dude, it'd be like there's a real St. Bernard there in the theater with you! The additional use of Smell-O-Vision would also do wonders.

Saw III
Why haven't they done this series in 3-D yet? A victim's-eye view of any of of Jigsaw's death traps would be a terrifying experience, and the sight of a ribcage getting torn open in 3-D sounds like a hoot. Ah, well -- maybe for Saw VII.

Beverly Hills Cop III
Maybe some 3-D footage of amusement park rides would have made up for this being a terrible, terrible film.

Transporter 3
While it would probably look awesome in 3-D, it might be cheaper to simply have Jason Statham drive an Audi through the back wall of every theater showing the movie. He was probably going to do that anyway.

Alien 3
Is that what this movie needed to make David Fincher's institutionalized vision really pop? 3-D? Because I'm picturing the multi-tiered prison and all of the bald domes and especially the final scene, and I'm thinking it was originally supposed to be in 3-D. Maybe we should go through and add 3-D to all of Fincher's films, just to see what happens.

Richard III
Granted, a filmed version of the stage play could only be improved by 3-D, but if the process was applied to 1995's alternate-reality version, set in fascist 1930s England and starring Mr. Gandalf P. Magneto as a wartime Richard, that would possibly be the coolest Shakespeare movie ever.

What threequel would you like to see as a 3-D movie?