To turn left, blink your left eye. To turn right, blink your right eye. To start moving, clench your teeth. To stop moving, clench your teeth again. Thanks to researchers at Miyazaki University, wheelchair users with limited muscular control will have greater mobility options.
http://www.diginfo.tv/2011/10/17/11-0213-r-en.php -via Popular Science
Tongue Studs Can Give Paralyzed People Greater Control Over Mobility Devices