The Skinput concept by Microsoft is another one of their latest innovations. Still in product development, this user interface for mobile devices uses a small device strapped to your upper arm that picks up small vibrations and muscle movement when tapping 5 different input points on your forearm and fingertips. An integrated Pico Projector can be added to project visual buttons on your skin. How is the accuracy? Well, the prototypes tested are 95.5% accurate even when running.
Personally I like the idea of controlling an MP3 player by tapping my fingers, but I don't see the practicality of the projected buttons if your wearing a jacket or long sleeve shirt... What are your thoughts?