Intelligent Systems Lab at Rensselear Polytechnic Institute, US. Using a stereo setup Zhu Zhiwei and Ji Qiang are able to produce a head movement tolerant eye tracker that calibrates in less than five seconds and provides around 1.6 deg. accuracy with 25 frames per second.
Zhiwei Zhu and Qiang Ji, Novel Eye Gaze Tracking Techniques Under Natural Head Movement, IEEE Transactions on Biomedical Engineering, 54(12), p2246-60,2007. download the paper.