Psylocke is an ios based real time emotion detection app. It uses the Fisherface http://www.bytefish.de/blog/fisherfaces/ to classify and predict one of the following facial expression:
Netural, Happy, Sad, Surprised, Sleepy, Wink,
Psylocke uses yale face database as training data http://vision.ucsd.edu/content/yale-face-database