Call of Duty: World at War. I've recorded over 30 hours of play already (Nazi Zombie FTW)!
I'm getting Gears 2 this Christmas, but I know that if I would have bought it this month, I would be playing right now! =P
Random game thought :
Why is Bionic Commando Rearmed 2 getting so much hate? We finally get a real game and they're not even satisfied... I'm starting to hate the gaming community so f****** much...