If you use Stickies (and are using 10.3 or newer) and have them display on a larger, external monitor with your Powerbook or iBook, you may have issues if you remove the external monitor. The next time you go to use your Stickies, you may find that they have moved off-screen (that is, they still believe that you have the other, larger monitor attached).
Fixing this is simple, but it takes several steps which have to be completed in the order shown. If someone knows a better way, feel free to post it, but be sure to test that it actually solves the problem rather than "It should work this way" -- as I tried some of those, and they didn't actually work for me.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050904215408987