ISeeAll has been working on a Halloween Moving Skull Project which used an Arduino that is monitoring 5 photo cells so that it can watch shadows of people walking by so that it can look at them. move to predetermined positions based on which sensor is shaded. I think a room with even one entrance can be made very spooky with something similar, just have an IR beam on the entrance so the head can move from a default looking away position to a direct stare at the doorway as soon as someone enters.