UPDATE (3:05 PM PT): Torchlight is now free for the next 3 hours. Go to http://www.gog.com and claim the game on the front page.
UPDATE (10:20 AM PT): Still Life 2 is free for the next 2 hours. Go to ttp://www.gog.com/ and claim on the front page.
Yeah, we have a GOG thread, but people will probably overlook this otherwise.
Basically go to http://www.gog.com/ and scroll down until you see Omerta on the front page. Click the free butotn and it's yours.
Offer good for the next hour
Edit: there will be three more free games later today