Philips Research/Orange have created a concept "game" based around a sensor that you rest between two fingers. The sensor reports on your relaxation level as measured by galvanic skin response, and assigns more points based on how calm you are.
(via Gizmodo)
Update: Eric sez, "The folks at The Wild Divine Project out of Boulder have taken this a bit further. They have a complete usb biofeedback system (based on three finger sensors that measure heart rate and skin conductance) that powers an adventure game. At each stage of the game you regulate your internal level of relaxation, excitement, etc. to perform tasks. It has a new age feel to the game, but they also have a more geeked out expansion pack that gives you live readouts of the biofeedback. A new title is rumored to be in the works."
