The "Tongue Mouse" isn't precise enough for gaming yet, but somebody's working on it.
Valve mechanical engineer Ben Krasnow has done the unthinkable. I was going to try and be witty or funny about it, but honestly my mind is so completely blown by the concept that I don't think my blog-humor could properly convey how crazy this invention is.
Ben Krasnow has created a mouse you can control with your tongue.
The controller, a little nub stabilized by a "retainer kind of housing," allows users to move a cursor by sliding their tongue over an infrared sensor after mapping "X/Y coordinates in a Windows-style UI with tongue movements constrained to a plane." Though the version he shows off has a big set of cables popping out the front, Krasnow said worked on both wired and wireless tongue mice.
Despite the tongue's level of fine motor control, Krasnow says the mouse isn't precise enough to replace a good old-fashioned mouse, specifically mentioning that using the it for gaming would "be impossible." Krasnow suggests that, rather than replacing our traditional control setup, the tongue mouse could be used in computing scenarios when a mouse and keyboard may not be available, specifically pointing to augmented reality and applications that rely on large swiping gestures.
Whether or not the tongue mouse useful seems irrelevant at this point. They're just prototypes: If Krasnow - or some other engineer - kept at it, they could fine-tune the features and find some kind of practical application. (Some commenters suggested "remote kissing software..." ) The point is: We did it and that's pretty cool.