Crackdown for Xbox 360
 

This game is amazing! The graphics aren't as wow as Gears of War, but the gameplay sucks you in and you don't even care. Jumping from rooftop to rooftop, picking up cars and hucking them, what else can you ask for? Play co-op with a friend for even more good times. As if this game wasn't awesome enough on it's own, you also get an invite to the Halo 3 Beta with purchase.

Between this, Gears, and Rainbow 6 Vegas I might as well sell off all my other games.