Your computer screen is dirty, so these vacuums 
are going to clean up the mess.
You get 100 points for each dirt pile 
picked up, and lose 1 point each time each vacuum does anything.
This hypnotic doo-hickey is based on exercise 2.5 from the Artificial Intelligence textbook. Don't worry, there isn't any real intelligence in these critters.
You can tweak various settings below.
Good luck!
Works best in Firefox. Works OK in Safari. Doesn't work in IE.