From Fast Company magazine:

"Tony Quan, better known as TemptOne, was a fixture of the L.A. graffiti and politcal-activism scene before he was diagnosed with ALS in 2003. The disease quickly rendered him unable to move anything except his eyes. In the intervening years, the disease has ended his days of graffiti writing--but he's tagging again, thanks to a new invention, the Eyewriter.

"It combines eye-tracking hardware and GRO's famed L.A.S.E.R. tagging system, which uses a laser pointer and an LED projector to create virtual graffiti as big as a building."

More here.