Chipwhich sent in this solar powered microbot based on a Picaxe (PIC with bootloader) -

This is a small solar powered progammable robot. It’s design was inspired by BEAM robots, but whereas those devices are usually entirely hardware based, I favor systems which rely on software. Allowing programmability, however basic, introduces a whole new level of flexibility.

This microbot is also called a vibrobot because it vibrates in order to generate horizontal motion. Because it is microprocessor controlled, it can sense stimuli and respond as programmed. The low power requirements of the components lend themselves well to solar power stored via a super-cap.

Solar Powered Picaxe Microbot (Vibrobot) – Link.