I practically died when I seen this one. Dan Thyer set up a Netduino operated garden hose which is controlled by a program that uses a servo to change the direction of the hose. By pushing a button, he's able to have the hose continuously spray water in a pattern which machos the inner lining of his pool.
He's also able to manually take over by using a kinect which uses it's skeletal tracking abilities to precisely control where the hose is directed. He can essentially sit on his porch and blast water at anyone in the pool with a fair amount of accuracy.