Here's an interesting application made with the Unity3D game engine: an interactive projection of a dog on a storefront window, complete with proper behavioral responses. (video has no sound)

If your gestures and body language are interpreted as friendly, the dog will respond to you the same way as well. Same goes with a show of aggresion towards the dog. The sidewalk is illuminated with infrared lights, and tracking is done with an infrared-sensitive camera.

You can see Sniff in action when it is hosted at The Change You Want to See gallery, during the Conflux Festival in New York this coming September 18th - 20th.