IOGraph [iographica.com] is a little software application that turns the continuous tracking of computer mouse movements into a modern art.
The basic concept is that people just "run" the application in the background, and then accomplish their usual activities at the computer. After a long day of hard work, a beautiful image is then created by cumulating all mouse movements and representing them as continuous paths. For people who work in a single application for a considerably long time, IOGraph could even provide potentially interesting usability data when overlayed on a screenshot of the actual window configuration.
You can check some past mouse-tracking art work at Flickr.