IOGraph maps your mouse movements on Windows, Mac, and Linux
IOGraph is a Java application that traces your mouse movements while you work. The screenshot above shows about 1:20hrs of my work, during which I took a break (it shows up as the large blob near the middle).
The reason there's a large blank area on the right side is that I have a dual-monitor setup. I usually use the right-side (secondary) monitor for displaying information, while keeping my main work area on the primary monitor. If you work in one application for hours on end (such as a graphics editor or a work processor), IOGraph can also provide interesting usability data when overlayed on a screenshot of your window (Photoshop, in this case, by the application's developer).
While the application does perform its main function (and is the only one I know of, in this niche), not all options work. For example, there's an option called "use desktop for background," which just didn't work, no matter how I tried to activate it (while recording, before starting, etc). If you do get it to work, tell me how you did it in the comments (or, of course, if there's a better app for this).