If you've been searching for a way to use your iBook in extended mode then look no more, Screen Spanning Doctor will do the trick.
Extended mode is where you use two or more screens together.
It's great if you're doing design work, want to share screens, or need more space. It also looks really cool, especially when moving windows between screens.
Screen Spanning Doctor will automatically change Open Firmware settings to allow extended mode in your machine. Just launch the application, choose 'enable spanning', restart, and you'll have extended mode.
Screen Spanning Doctor won't work with all machines though, so you'll have to make sure your Mac is supported before testing it out. Also be aware that it can have unpredictable effects on your Mac, simply because it isn't officially supported by Mac.
That said though, it really is the easiest way to activate extended mode on an iBook in seconds. You can also simply choose 'disable spanning' to stop using it.