YouTube user GusJanss made an awesome Mindstorms walker that uses only 3 NXT servos to move six legs. Nice hack!
The Hexapod Walker is a six legged LEGO NXT robot walker. It uses a gait that causes very little slippage at the feet so can walk well with rubber tipped feet all the way around. The left and right motors control their respective sides corner legs. The motor in theback controls the middle set of legs so that either left or right corner legs can be lifted. When left middle goes down, left corner legs go up and right middle goes up.
First program just walks in a simple pattern. The second program was for a walking robot race and uses the small LED lights as navigation aids. Light sensor, mounted in the back but looks forward, sees the light and with every step adjusts step size to aim for light.
[via the NXT Step]