Dead Space 3, SimCity, Crysis 3, or Army of Two: The Devil's Cartel, you get a code for $20 credit towards future purchases. Yes, that credit's tied to Amazon, regardless it ain't to be sniffed at.
There are other pre-order bonuses tied to some of these games, such as the Limited Edition goodies and Amazon-exclusive Enervator gun for Dead Space 3. The SimCity pre-order gets you access to its Limited Edition as well as the beta, which runs this weekend. Crysis 3 bundles in the original Crysis, and Amazon's exclusive is the Brawler Pack.