The April issue of Wired magazine has a very nice display of photographer Phillip Toledano's series Game Faces. He set up an XBox and a strobe so he could directly shoot their faces as they played a fighting game called Dead or Alive. It's a cool series but sadly not available online at the Wired site so if you're not a subscriber look for Wired in your local bookstore.

Update Aha! Mr. Toledano has the series on his website (the navigation for it isn't the most intuitive or helpful but I'm sure you're figure it out).