Having some fun experiementing with jsfeat.
Simple web app that looks for features in a picture that might be a human face. Very sensitive to lighting and really only works with a front-profile shot. Still though, pretty awesome.
js feat provides comptuer vision JavaScript algorithms that can be run in the browser! Well sort of. Your browser must support WebRTC. Chrome does this natively. IE and Safari will do this with a plugin.
You need a connected camera to your computer in order for this to function.
Credits and More about jsfeat: http://inspirit.github.io/jsfeat/