Right now it is MW3, BF3, and RB3. While we are here what kind of music do you listen to while playing if you do? I will listen to music that goes with the game or what I feel like listening to at the time.
Gears is the only multiplayer game I enjoy, so it's the only game that I'm consistently playing. Other than this, I just play solo games. I just beat two that I was playing, and I'm thinking I'll be going back to Assassin's Creed: Brotherhood to finish that off next.
As for music, I tend to just listen to in-game music/sounds. Rarely if ever do I put other music on in the background.