RealEye - Online Research Platform with Webcam Eye-Tracking.
TrackIR - TrackIR adds depth to the PC gaming experience by enabling players to take control of the in-game view.
Tobii Pro Lab - Eye tracking software for behavior research. Combination with other physiological data while you design, execute, and analyze with heat maps, gaze plots.
FaceTrackNoIR - FaceTrackNoIR is only available for Windows-based PC's (sorry, we have to start somewhere) and...
SeeSo.io - SeeSo, the real-time eye tracking SDK for the smartphone/tablet/laptop environment. With a users' vision, reach beyond the vision.
linux-track - Linuxtrack is a software bringing headtracking to Linux and Mac OS X.