XBL has been booming the last few days. Here is a sampling of things recently added:

Chromehounds - New Weapons/Colors/Items
Viva Pinata - New Episodic Videos
Just Cause - Trailers and DEMO
Texas Hold Em - Was free for 48 hours
Samurai Warriors 2 - A Crapload of Download Content (before the game is even out!)
Test Drive Unlimited - New Demo
Oblivion - Vile Lair DLC
Red VS. Blue - New Episode

Check out Live for these and a lot more!