Came across the GazeLib low-cost remote eye tracking project today which uses ordinary webcams without IR illumination. The accuracy is pretty low but it's really nice to see another low-cost approach for assistive technology.
"GazeLib is a programming library which making real-time low-cost gaze tracking becomes possible. The library provide functions performing remote gaze tracking under ambient lighting condition using a single, low cost, off-the-shelf webcam. Developers can easily build gaze tracking technologies implemented applications in only few lines of code. GazeLib project focuses on promoting gaze tracking technology to consumer-grade human computer interfaces by reducing the price, emphasizing ease-of-use, increasing the extendibility, and enhancing the flexibility and mobility."