Direct2Drive has a two for the price of one on select games.
Saints Row The Third/Saints Row 2 - $50
Arkham City/Arkham Asylum - $50
Dragon Age: Origins Ultimate Edition/Dragon Age II - $30
Fallout: New Vegas/Fallout 3 Game of the Year Edition - $20
Those are the highlights, but here is a link to see the rest.
It ends soon btw.