On the latest PowerBooks, you can scroll by moving two fingers on the trackpad.
I discovered yesterday while browsing around in the Finder that if you keep one finger still while moving the other, whatever you are scrolling will scroll very slowly. It is really handy if the text you are trying to read is small, for example.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050928074128333