4th Edition Dungeons & Dragons
Star Wars Saga Edition
Mutants & Masterminds
Truth and Justice
Castles & Crusades
Forward . . . to Adventure!
Stargate: SG-1 Roleplaying Game
EDIT: Iron Heroes
The games that I currently want to play; this leaves out d20 Modern, 3.X Edition D&D, GURPS 4th Edition, and Risus, because I've already played them, and I'm currently in a new system mood.
There are probably a few more I've forgotten. These are in the order of "estimated likelyhood to play," based on ease of access to materials and interests of potential players. 4th Edition is at the top because I'm absolutely getting the books, and barring natural disaster or mutiny I'm going to be playing at least a couple of sessions of it.
Stargate is at the bottom because it's out of print, and the books on Ebay cost over $60. Otherwise, it would be very close to the top. Curse you, Sony!
Everything else ought to be fairly obvious . . . I know more people who are into Star Wars than superheroes, it's easier to get people to play d20 than weird, newfangled systems, and I don't know many people who share my mostly unrealized fascination with old school gaming.