I hate to be that guy, but this "deal" comes out to cost regular price for XBL. Net price of $20/4 months is the same price per month as a year from amazon or XBL ($60/12 months). :(
I'd be all over KOTOR 3 and Republic Commando 2. I played both Battlefront games, but I was never that impressed with them. It's probably because there's almost no plot to the games.
I attended Uproar fest. The bands featured were Avenged Sevenfold, Bullet for My Valentine, Seether, Three Days Grace, The Art of Dying, Hell or Highwater, and Sevendust.
Assassin's Creed: Revelations
Deus Ex: Human Revolution
A few Xbox Live 3 month cards
Borderlands: GOTY
Gears of War 3
Possibly Skyrim (I have a huge backlog, so I might wait for a better sale)