There’s a 20% discount on all purchases at the store after promotion code.
You can use it on Skyrim, which would be ~$48. The game uses Steamworks so you’ll have to activate it on Steam. The daily deal for their Black Friday sale is RIFT Ashes of History Digital Collector’s Edition, which would be around ~8. Other choices would be a pre-order on Assassin’s Creed: Revelations, which would be around $34. Mass Effect 3 Digital Deluxe Edition would be $57.56.
To get the discount use the following promo code at:
These promo code are live for today only!
EDIT: Also, you could use the promo code on Modern Warfare 3. This game will probably rarely go on sale. After the promo code it’s only $48, plus it activates on Steam.