I got Quake 3 running, the frame rate was pretty much why bother land, and I had no sound of course, but still, that was nice. It would probably run faster if I launched it from the command line rather than the GUI yeah? Since this is linux we're talking about I imagine I'd have to rewrite my sound drivers in assembler and make my own custom firmware after soldering something to the circuit board of this thing.
No success with Quake, I'm sure it would be easy to set up for the Gurus but since I have no idea what I'm doing I hit a wall. I'll try again later.
Next I'll try Raspbmc, if I can get that going I suppose that'll be something actually useful I can do with this thing:
http://www.howtogeek.com/119924/build-a-35-media-center-with-raspbmc-and-raspberry-pi/
That page also says expect to wait 4-5 weeks for your pi. That's pretty funny! I ordered mine in April and only just got it now!