Here are my favorite sites for group buys (usually half-off deals):
Seize the Deal
Check out Swagbucks to earn amazon.com gift certificates and many other valuable rewards.
It's easy to search through swagbucks and win!
This is my favorite site for finding swagbucks deals. Look at her recent posts in the sidebar for her daily swagbucks post entitled “Winning Ways on Swagbucks”. (Be sure to check out the list of stuff she has won with swagbucks!)