I bought a few games from the Steam winter sale, including Edge for 79 cents (90% off). It's a cool little puzzle/platformer game, and for 79 cents you can't go wrong. Also, Mortal Kombat for $10. I also highly recommend Mark of the Ninja, which is on sale for about another 20 hours for $2.99. It's a stealth game and one of the better games I played last year.
Just bought Resistance 3 on PS3 for 12$ at a local pawn shop. I liked 1 and 2, but that was a long time ago. So I'll give this one a spin in the next few days.
March is almost here, so beginning this Saturday you can enjoy two more titles via the Xbox 360 Games with Gold program, available for free for a limited time*: