FaceOSC

FaceOSC is a tool for prototyping face-based interaction. It's built on non-commercial open source FaceTracker code from Jason Saragih. Download it here:

https://github.com/kylemcdonald/ofxFaceTracker/releases

FaceOSC comes as an example app with the ofxFaceTracker addon for openFrameworks.

OSCulator is an excellent program for routing OSC and MIDI. Download it at http://www.osculator.net/

Some of the "face gestures" (or metrics) are more stable than others. Lighting can also have a huge influence on the stability of your values: even lighting from the front coupled with a dark background can give the best results.

Some of the first demos from others:

http://vimeo.com/26188365

http://vimeo.com/26161519

http://vimeo.com/26301657

http://vimeo.com/26475997

http://youtube.com/watch?v=ArG3t_OOYis