Seriously, if you are not using GOG, get it. They give away free games every now and then I have gotten: saints row 2, mount and blade. They also gave away the witcher enhanced for free (missed that one though). The time you can get them though can vary quite a bit from half a day to a couple of days. You keep the games once they are no longer available for free and you can download them at anytime once you have got it. Pretty good, eh?
Buying games on there can have advantages too as all of the games on there are DRM free. This means you buy it, you keep it forever. You can copy it around and back it up. And there are no checks, which means that you don't have to have any clients like steam installed. You essentially get the freedom of a game that you would get on disk, except you don't need the disk.
