It is no secret that you can learn a lot about electronics and robotics by building and customizing your own Arduino robots. This guide from joesinstructables shows how you can build your own Arduino Quadruped Robot. Stompy was built using 8 servos. As the name suggests, it achieves a stomping type of walk.
You are going to need an Arduino Mega, servo brackets, IR distance sensor, laser, and a few other parts to put this robot together. More info is available on Instructables.com.