This hint points to a really in-depth, hi-resolution take-apart tutorial (on Youtube) about opening, cleaning and closing a dirty wireless Apple Mighty Mouse, presented in English. This is the way to do it after you've tried cleaning the ball from the outside 100 times. Save your mouse from the scrap heap.
Here's the link.
[crarko adds: We've run other hints on this before, and it's been quite a popular topic. A video tutorial seems like a good follow-up.]
Mac OS X Hints