Perceptual user interfaces (PUI) are systems that use users' motion - such as the motion of the face - to control a software program.

A technology developed by NRC-IIT, Nouse - which stands for "nose as mouse" - is based on tracking the rotation and scale invariant nose feature, defined as the closest point to the camera.

The main application of this technology is seen in designing intelligent hands-free perceptual user interfaces to supplement the conventional input devices such as mouse, joystick, track ball etc.

read more: http://synapse.vit.iit.nrc.ca/Nouse/index2.html