Eye-tracking Control - Important to note--not all eye-trackers serve all users; each is designed for particular needs which means try no less than three of them before making a decision on accuracy and effectiveness for the user. One may work for some users and not others, and vice versa.

The Eyegaze Edge
http://www.eyegaze.com

Eyetech
http://www.eyetechds.com/

Tobii
www.tobii.com

ComLink LT3G Enable Eyes
http://www.frs-solutions.com/products/comlinks/lt3g_enable_eyes

Eyemax:
http://www.dynavoxtech.com/products/eyemax/

ECO2
http://www.prentrom.com/