Randy Sarafan just made another simple moving bot, this time with four legs for walking:

My goal with Walker Bot was to make a 4-legged walking bot that could be made in ten minutes. This bot ultimately took me three hours to make. That said, my goal wasn’t to make one in ten minutes, but to make one that could be made in ten minutes. I am pretty confident that now that I know what I am doing, should I need to make a second one, I could do it in ten minutes. At the very least, you will be hard-pressed to make a simpler walking bot than this one. I would consider this project a glowing success.