So, I think this might be the first game I've actually been excited about for a long time!
http://masseffect.bioware.com/

ME3 is coming out in March, but there's some pretty sweet stuff going on right now too:

Preorder the game and you get bonus items - armor, weapons - depending on who you preorder from
http://masseffect.bioware.com/me3/game/

Download the demo for Kingdoms of Amalur:Reckoning (must be an Xbox Gold member) and you get new armor, and a new gun if you play the demo all the way through.
http://news.teamxbox.com/xbox/25602/Unl ... alur-Demo/

Kinect functionality!
Now you can yell "Shotgun!" and your character switches to the shottie. You can even tell your teammates what biotic powers to use by saying their name and the power you want them to use.