PS2 - GTA3, Project Zero 2 (Fatal Frame 2 in America), Pro Evolution Soccer 4.

PS1 - Star Ocean 2 (hardly ever play it though).

GC - Mario Kart, F-Zero (multiplayer)

PC - Unreal Tournament 2tk4 every now and again. That online triple triad game.

I don't spend that much time on games though, I've been on gta for ages and I've only just finished the last of the .hack games (not bad but fairly dull after a while). Still got Star Ocean 3 to play yet.