OK, this is petty, but I've had a problem with 'schmutz' gathering on the nylon slides on the underside of my mouse. This makes the mouse movement a little jerky (even with my optical mouse), and requires that you stop occassionally and scrape it off.
Here's my solution: a little furniture polish on the underside of the mouse. Put it on a paper towel first and apply it only to the slides: avoid getting any on the LED section. This keeps the mouse cleaner longer and improves its usability.