My son and I wanted to build a little 6-legged walking robot as inexpensively as possible. We used craft sticks, fishing line, some eye screws, pipe cleaners, and a single motor, plus some electronics. We used an Arduino for the proof of concept, and then two 555 timers (which became the eyes) to let it roam untethered. It was a great learning experience for the kids, and now we're even working on putting together a kit version for some schools and other individuals.
I have a lot of photos and videos on my website at http://www.thefrankes.com/wp/?p=2459.
I hope you enjoy it!