Solarollers serve as the starting point for many BEAM enthusiasts.  They are simple to build and easy to design.  Electronically, they are no more than a solar engine with wheels.  By, storing energy and releasing it in a rather short period of time, they can achieve remarkable speeds.  They are very fun to watch but are dangerous to leave by themselves in direct sunlight.  I have had a couple jump off of some very high places while I was away.

Solaroller 01: My first ever BEAM robot
For this robot, I used a nice tutorial that can be found at BEAM Online.  The robot is really quick and changes direction quite often.  It has enough power to knock over other robots in its path.