Anatoly Zenkov provides this nifty tool (Mac and PC) to track your mouse pointer. Really simple. Just start it, let it run, minimize the window, and carry on as usual. In the end, you get this image that looks something like a Pollock. Circles show areas where the pointer didn't move while the tracks show movement.
The above is my own activity during the past couple of hours. I was just randomly browsing while watching the Laker game, so it's kind of all over the place. Run while using a single application for a while, and you might see something like Zenkov's tracks on Photoshop.
What do your tracks look like?
Update: Anatoly has setup an actual site for the app instead of it sitting in the dropbox boonies of boontown. Go there for the most up-to-date info.