Humble bundle is giving away free copies of Metro 2033 and will be giving out new games every 24 hours for a while. Please feel free to update this post so we can all enjoy the free games!! https://www.humblebundle.com/store
Thanks for the link snowman. gog are also doing a free game for 24 hours. I know its an old game but a free game is a free game. The game is little big adventure. http://www.gog.com/