Own an ATI Radeon card? Then you can get free games on Steam from ATI. Specifically you can get Half Life 2:Lost Coast and Half Life 2: Deathmatch. And, in the future if you buy an ATI Radeon HD 2900 XT you will be able to get Portal, Team Fortress 2 and Half-Life 2:Chapter 2.
You can check it out here.