I've already seen this before on a news article but a fish tank 'car' - it's basically a tank on a RC car body that uses a camera to detect the fish movement and drive the car around! There's a video of it someone. The developers tested it with a betta and he learned to drive around obstacles and follow around a person! How great would it be to be sitting at home having a nice chat with some visitors only to have your fish casually drive passed!! I want this.
Anyone looking for an automatic feeder that can be used with pellets and allows for controlled portions should check out the Fishmate F14 feeder (Amazon.com : Fish Mate F14 Aquarium Fish Feeder : Pet Self Feeders : Pet Supplies
) - I know I've recommended it several times to others but I really love it. I have one for each of my tanks that I use when I'm away. The only downside is that they are battery powered so you need to always check the batteries are working.