Steam has a bagillion deals going on, but one I'd recommend jumping on is Mafia II... for a mere $12.49. Or $14.99 for the "deluxe" edition (includes one of the fastest cars in the game, digital map, soundtrack).
http://store.steampowered.com/app/50130/
http://store.steampowered.com/app/50460/ (Deluxe)
http://store.steampowered.com/app/50130/
http://store.steampowered.com/app/50460/ (Deluxe)
