get free Battlefield: Bad Company 2 for steam : http://steamstore-battlefield2.pcriot.com/

Other game on this list :
ATI Card Owners
http://steampowered.com/ati_offer1a/
NVIDIA Card Owners
http://steampowered.com/nvidia/
America's Army 3
http://store.steampowered.com/app/13140/
Battleforge
http://store.steampowered.com/app/24770/
Between
http://store.steampowered.com/app/29140/
Codename Gordon
steam://install/92