The TrackIR2 is an infrared head-motion tracking system. It can be used with any first-person game that uses the mouse for looking around (i.e. my favorite, Thief II) and will translate any head movement into a mouse movement. You may be thinking (as I did) that moving your head while watching the screen is uncomfortable or impractical, but apparently the TrackIR only requires a modest head movement to work, so you can look at the screen while your mind is tricked into thinking you’ve made a more substantial rotation, and essentially simulating the effect of a much more expensive head-mounted display. The device works by tracking the movement of a reflective dot on the user’s forehead, so there’s no need to strap a big bukly device to your cranium. Sounds dizzying, but fun. Price is around $130.