Mr. General is a solderless breadboard on wheels — one of my favorite ways to play with robotics. Mr. General puts it all on a sturdy frame, throws in a nifty servo-operated object detector, and even 140 colored wires. You supply the microcontroller; I recommend a small all-in-one board, like the BASIC Stamp, Boarduino, or Arduino Mini Pro.
The circuit board provides power to the four servomotors included in the kit: two for the wheels, and two smaller motors for a pan/tilt turret, where you mount the “compound eye” proximity sensor.
This kit requires extensive soldering, and a build time of 4–6 hours. Using 1.2V rechargeable batteries, you can power a 5V microcontroller without a voltage regulator. For controllers that need 7V, use a boost circuit like the Pololu Adjustable Boost Regulator (pololu.com #799), but power the motors from the batteries.