Chip maker Analog Devices has some interesting demos in its booth, such as this electrooculogram (EOG) system that tracks eye movement based on tiny voltages generated by the eye muscles. Other than medical applications, such as lazy-eye rehabilitation and quadriplegic assistance, such a system could be used to control game play or even an entire home theater. Of course, wearing those electrodes wouldn't fly with consumers, but a future version could incorporate them into a goggle headset.