Seems like EA is celebrating the 12th anniversary of Command & Conquer by giving away something new each week in September. Today, it is giving away copies of the original Command & Conquer game. I've just downloaded mine. Have fun!
UPDATE@1630: Oh my goodness!! Ubisoft decided to release free games as well!! Get your downloads for FarCry, Prince of Persia: Sands of Time, and Rayman: Raving Rabids too!! Is there something going on in the PC gaming world?? I don't know what it is, but keep it up!!
UPDATE+1: Ghost Recon!