I only just found out about the sale but noticed no one has posted. Better late than never. The holiday sale started on the 21st but it runs till the end of the month. The following games will be on sale for the whole duration.
Super Meat Boy Discounted Price: 800 Savings: 33%
Comic Jumper Discounted Price: 800 Savings: 33%
Toy Soldiers Discounted Price: 800 Savings: 33%
Banjo Tooie Discounted Price: 600 Savings: 50%
Castle Crashers Discounted Price: 600 Savings: 50%
The UnderGarden Discounted Price: 400 Savings: 50%
Risk Factions Discounted Price: 400 Savings: 50%
Afterburner Climax Discounted Price: 400 Savings: 50%
Borderland's Claptrap New Revolution Discounted Price: 400 Savings: 50%
Carcassonne Discounted Price: 400 Savings: 50%
There are also daily deals
Dec 21: Red Dead Redemption DLC: Saving 25-50% (expired)
Dec 22: Lara Croft & the Guardian of Light: 600 Savings: 50% (expired)
Dec 23: Castlevania Harmony of Despair: 600 Savings: 50%
Dec 24: ?? (guessing Alan Wake DLC)
Dec 25: ??
Dec 26: ??
Dec 27: ??
Dec 28: ??
Dec 29: ??
Dec 30: ??
Dec 31: ??
Free 2011 glasses for your avatar :P
http://marketplace.xbox.com/en-US/Product/2011-Glasses/00000…