Two for the price of one. 30% extra. Get the coupons for one free. Those kind of promotions are used by marketing departments long time ago. But games haven't see those kinds of things often. The closer thing we had to those promotions are the Game of the Year edition, who usually are cheaper versions of famous games with all DLC included. But those don't feel like rewards for the costumer.
EA have done something quite smart to change that. You can hate EA all you want, but this promotion is very clever. If you download the demos for Mass Effect 3 and Kingdoms of Amalur: Reckoning, you can unlock free DLC for each game. This is very clever.
Mass Effect fans will play the demo of Amalur for the DLC, but like me, they can ended up enjoying the demo and buying the game. Possible Amalur costumers will play the ME3 demo and might buy the game, if they already wasn't doing it anyway, It is a scheme who raise awareness of both franchises, bring up possible costumers and give them small rewards for their loyalty.
Gamers are, in general, very picky. It is all about what they think they deserve, not what they really deserve. Rewarding loyal costumers, even with small things, make them happy. Dog-tags in Battlefield 3, some unlocks in Final Fantasy XIII-2. All those small things make the costumers happy.
I think game companies must do those things more frequently. Oh, you have several saves of our games? Here a free character skin. Bought the first game? Here a DLC. Played the demo? Here some extra skills.
Small things like that matters to gamers. If more companies do initiatives to reward, even small rewards like that, loyalty, the costumers will tends to remember those things. And will respond by spending more time and money with those games and their makers.