Games that I can remember:
Crackdown (overrated)
Forza 2 (not my thing)
Shadowruin (I'm staying away based on what I've heard of this)
Some nice XBLA releases:
Aegis Wing (not that great but it's FREE)
Prince of Persia Classic (attractive remake of the original POP, time limit and everything included)
TMNT The Arcade Game
Castlevania: SOTN (must get if you don't own the original)
Eets! Chowdown (Puzzle game with shades of Lemmings, includes another addictive game called Marsho Madness)
Super Pac Man (trippy sequel to Pac Man)