I've never noticed this before installing Mac OS 10.2.5, but it's a nice touch:
If you are running dual monitors of two different resolutions, and have a window open on one screen that is too tall for the smaller screen, moving the window to the other screen causes it to automatically resize to fit the other monitor. I have found this to work in Safari and many other Apple apps, but it doesn't seem to work in iTunes 4, the Finder, or in any Carbon apps.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2003050119210895