Blogger Signaltheorist decided to evaluate the efficiency of the Roomba by tracking its movements:
I set up a photo camera in my room, turned out all the lights and took a long-exposure shot of my roomba doing it's thing for about 30 minutes. The result is a picture that shows the path of the roomba through it's cleaning cycle, it looks like a flight map or something. It really hits every spot!
Link via J-Walk Blog