Castlemakers has had a long history in building robots. We’ve made brushbots and light seeking robots, and more recently started working with Makebots & Lego EV-3’s.

If you’re interested in Brushbots, you can read about them in these spots:

• An early writeup, we’re building some like this.
• Good ideas for modifications at this website, we have similar pager motors.

We’re also explored a more involved arduino-based on the Robobrrd, a bit dated now but here’s what some other folks did with it:

http://robobrrd.com/community/