A face detection computer vision program runs on a PC and sends the information to an Arduino controller connected via USB. The Arduino controls four RC servos which drive the eyeballs of the skull. Each eyeball gets controlled by one pair of servos, one servo for movements on the X axis and one for movements on the Y axis.
The result is that the skull's eyeballs are following you as you move around the room (in realtime).
This is a prototype for an idea I had. It's about having shop window dolls look at the crowd as it is walking in front of them. This would make the shop window interactive in a subtle but novel way and capture the audience's attention.