You need to play Double Dragon: Neon now. Since the first level I've been instantly sucked in to this beat-em up based on the 80's franchise. Humorous, fun and colorful the game is the perfect beat-em up to spend a few hours with a friend. You can get in on both the 360 and PS3 now. If you have PS Plus it's free, that's rather kind. I'll have a full review coming up and it's obviously going to be positive with me using many refrences to fighting.
Also, get Spelunky if you can already!