At the moment I'm in 3 Groups where we also switch between different GM's/Campaigns. At the moment we have three 4E Campaigns, two with Savage Worlds and one with Ars Magica.
We also love to test new Systems with One-Shots, the Recent ones where Dungeon Slayers, Warhammer 3E, Hackmaster Basic and 3:16. And quite a few are in store for the next ones, like Doctor Who, Barbarians of Lemuria and Dragon Age.
but i have played a few games at conventions this past year.
Cineplexity
Heroes Unlimited (made a PC but didn't play it)
Trivial Pursuit
Last Night on Earth
Mutants & Masterminds
Carcassone
Savage Worlds
Geist
Red Box Hack
Munchkin
Paranoia using Dread mechanics
Car Wars (1981)
Chez Geek
Call of Cthulu
CMG Mark's miniatures game
going to GaryCon2 next week. i should be getting in a few more non-D&D games. i'll post after the convention if i remember this thread.