
The Big Trak is possibly the coolest toy that has ever been made. It was basically a programmable tank that you could set to follow specific patterns. Made and sold in the 1970s, I drooled over it in the Sears holiday Wish Book, but never ended up with one.
This site has pictures, manuals, how-tos and all other kinds of stuff you need to get your own Big Trak, and program it.