Not sure if this counts as a robot, but it does use a servo and has a circuit. This is my second useless machine actually, the first one I sold to a friend. The first one I slapped together but the second one I designed on the computer first and then measured out all the parts, trying to get it as small as possible. The limiting factor was the battery case which holds 4 AA's.
Actuators / output devices: one servo
Control method: DPDT switch
Power source: 4x AA (1.2V) for powering the servo's
Yea, I saw that one. Laughed a lot along with my collegues whom I showed it to later. It’s a classic. When I get better at programming the picaxe etc I might have a go at building something like it.
Saw you guys covered it in Latest in Hobby Robotics too.