An interesting follow-up question: what current-generation games do you think you'll still play regularly in several years?[/quote]
Deus Ex for PC is in between old and new, but I play it every year and will continue to do so. Since I'm talking in between, add Parappa, Um Jammer Lammy, Destruction Derby 2, Mr. Driller, and Pokemon Snap to that list.
As for PS2/Xbox/GC games, I'd say Animal Crossing, Monkey Ball, Amplitude, Katamari Damacy, Burnout 3, and Star Wars: KOTOR.