Sometimes when I'm looking at weird game/computer controller, I run across good things. Tonight I found this breath-based controller by David MacKay; it's still a bit rough but it exemplifies the idea. It actually connects lung volume to the mouse y-coordinate More about it in the following paper: Efficient communication by breathing by Tom H. Shorrock, David J.C. MacKay, and Chris J. Ball.

The arithmetic-coding-based communication system, Dasher, can be driven by a one-dimensional continuous signal. A belt-mounted breath-mouse, delivering a signal related to lung volume, enables a user to communicate by breath alone. With practice, an expert user can write English at 15 words per minute. (...) first breath mouse, made from an optical mouse, a belt, and a piece of elastic. The mouse is fixed to a piece of wood, to which a belt is also attached. Two inches of the belt are replaced by elastic, so that changes in the waist circumference produce motion of the belt underneath the eye of the mouse. This sensor measures breathing if the user breathes using their diaphragm (rather than their rib cage). We oriented the mouse so that breathing in moves the on-screen mouse up and rotates the pointer anti-clockwise along the curve; and breathing out moves the on-screen mouse down and rotates the pointer clockwise. The sensor also responds to clenching of the stomach muscles, but we encourage the user to navigate by breathing normally.

And yes, this is a breath mouse:

Why do I blog this? even though it seems funny, sometimes weird controllers (in this context, the point was rather engineering-based than creating a new product) end up into nothing but gives some ideas about the future of interactions.