If you have an IR capable webcam lying around, here’s an interesting open source project you may want to try. “The ITU Gaze Tracker is an open-source eye tracker that aims to provide a low-cost alternative to commercial gaze tracking systems and to make this technology more accessible. It is developed by the Gaze Group at the IT University of Copenhagen and other contributors from the community, with the support of the Communication by Gaze Interaction Association (COGAIN).”
The eye tracking software is video-based, and any camera equipped with infrared nightvision can be used, such as a videocamera or a webcam. The software requires a computer running Windows XP with Service Pack 2 and .NET Framework 3.5 SP1.
The development crew encourages users and developers to test Gaze Tracker with their cameras and provide feedback to assist in further development.