Just go to the Visa Signature Holiday site:
Click on SMG2 to get your coupon code (you need to enter your Visa Signature card number).
Then, head to Amazon and add SMG2 to your cart and enter your one-time use code at checkout.
STILL AVAILABLE: They're also offering $15 off Halo Reach, which would knock it down to about $35 which is what most places had it for around Black Friday.
Edited by aaronmills, 02 December 2010 - 11:12 PM.