The old Shuttle toilet trainer. There wasn't any plumbing down the hole, just a camera with a closed circuit monitor (just out of picture to the right) that would let you check your aim before going to do the deed for real on the plumbed model. Fun stuff!
HOLY HELL I JUST NOTICED THESE!!
Both are awesome, although I don't know how I feel about a camera to "check my aim". I think there are parts of my bodily functions better un-observed by me.