Latest Update: New 4WD base with omni wheels- see new 'QwerkRover' project!
My first robot. I added a couple of features to the "Qwerkbot+" recipe- a sharp IR distance sensor for input; a couple of ultrabright LEDs for at-a-glance status indication; and a loudspeaker for audio playback. The base had two wheels for differential drive, plus a castor to balance. The webcam and IR sensor are then mounted on a pan/tilt unit (two servos).
Programming projects on this configuration included edge-detection for static object tracking; collision avoidance for autonomous roaming; and cliff avoidance for driving around on tables.
I maintain a 'blog at the address linked above, with details of my latest hardware build and coding progress.