NaturalPoint TrackIR 5
Need that extra edge when playing your favorite FPS? NaturalPoint’s TrackIR5 will supposedly track your head and convert the movements for the game you’re playing, providing six degrees of freedom, including pitch, roll, yaw, and XYZ. Unlike a standard mouse, the device clamps to the LCD screen much like a webcam, keeping track of your chair and head rotation. In a first-person sense, this eliminates “mouse-look” and instead matches the game’s perspective with the angle of your head.
You can buy a TrackIR 5 on NaturalPoint for $149.95.