Michael Reeves is a software developer at Infibit that has made a face tracking robot that is housed in a Pizza Box, it tries its best to find your eyes and shine a Laser in them. The software that runs on a PC was written in C# and uses Emgu CV which is the .NET version of Open CV for the facial recognition portion. A web cam is connected to the computer scans for a face to attack, when detected the coordinates are sent over a serial cable to a microcontroller.  The ATmega 328 microcontroller has a few servo motors connected to laser pointer. Since the servo motors can move the laser pointer in XY positions the coordinates are used to point where it needs to. The result will annoy you and your guests. I think this would be useful at popular store displays when you need people to move along after having a quick glance. If you are looking to build your own version you can find the code here.