Has anyone made this? (Face Capture For Your Images)

I have a ton of pictures that have anywhere from 1 person to hundreds of people in them.  What I thought would be very cool to have as a utility, software that can scan your pictures and select the faces out of them and take a snap shot of the face so you can then do an analysis of what the average expression or mood a person is giving. 

\"I wonder\"

Thinking more about this is actually making me want to learn how to program.  I mean how cool would it be if you can figure out what your friends or family members average mood is by the facial expression you capture in an image.  Eventually you can use this type of software to do statistical studies of large groups and even kiosks or advertisements.