uControl
For the fellow PowerBook users out there, I just found a very useful utility (uControl) that lets you turn your trackpad into a virtual scroll wheel when holding down a key of your choice! Very useful for reading web pages. uControl will also let you remap your keyboard, so (if you have a 15- or 17-inch PowerBook with keyboard backlighting) you can reclaim use of the function keys for controlling Exposé, which is now my favorite part of the OS X GUI.
