Wear Your Mouse - Essential Reality's mouse-glove offers alternative input

If you dislike having to clamp your hand on a mouse all day or if you have
problems holding your wrists in a certain position, consider this strange
concept: mousing in mid-air. Essential Reality has developed an odd-looking
hand contraption that lets you control your mouse when you flick your fingers
and wrist in various (and customizable) ways. The P5 is designed to take
advantage of 3D games but could also be a useful alternative to desktop
navigation and mousing around in certain applications. 

http://www.essentialreality.com/products.html
http://www.essentialreality.com/media/macworld.pdf