For those who want to build their own real-time eye tracking system, downoad the open-source code here. Video demonstration after the jump.
The purpose of openEyes is to provide a hardware design and a set of software tools useful for the analysis of eye movement data. The tools available for this platform include algorithms to measure eye movements from digital videos, techniques to calibrate the eye tracking system, and example software to facilitate real-time eye-tracking application development
[via HackedGadgets]