The website HotDeals has a feature called 'Spin to Win', where you can spin a wheel once a day to earn up to $10 in Amazon gift card codes. As is, this is a rather nice set up (since you just need to remember to go back every day and spin).

But what makes HotDeals even better is that for every person you refer you earn 1000 coins which can be translated into 10 more spins. You could potentially win up to $100 for every person you refer to HotDeals.

Amazon code redemptions start at $0.50, with a a $0.35 deduction fee for every redemption (so redeem at higher values than lower ones.)

Check out HotDeals @ http://www.hotdeals.com/ and start earning free Amazon gift card codes. 
( Or you could be awesome and sign up under my referral: http://www.hotdeals.com/?mktsrc=referral_copylink_53e6155d6dc4c )
Either way, happy spinning!