QTrack is a fast, robust face tracker for use with OpenCV. It adapts automatically to changing lighting conditions, which makes it more robust than Camshift. Yet, it is faster than Camshift by about 20%. Unlike Camshift, which must be carefully tuned by hand for each use context, QTrack has no parameters. It is fully automatic and self-calibrating.
QTrack version 0.90 is available for download under the BSD license. It uses an internal OpenCV cascade for face detection and has an extremely simple API. You only need to call one function to detect and track the centermost face. This is the most common use paradigm in applications that do face tracking, so QTrack's minimal API should meet most users' needs.
Currently, I only have a Win32 release.