We (I) have a 14" G4 iBook. It's quite the nicest laptop I've ever used.
Software picks:
1. Mail is quite sufficient for most folk.
2. However, you want Camino for web browsing.
3. MSN Messenger further demonstrates my theory that Microsoft should abandon Windows because they're really much better at writing very nice Mac software.
4. Office v.X - see (3).
5. I found a decent IRC client - X-Chat Aqua.
6. iChat is fabz0r for gassing to your mates.
7. Tinkertool is also a great way of wasting a vast amount of time.
8. UNIX-heads will spend what little time they have left (after 6 and 7) playing with Fink.
9. You get XCode with it! It's great! Even *I* can write programs with it.
10. Move the dock to the left, as small as poss, and auto hide it.
My overall feeling I get when using the iBook is, "This is how it's SUPPOSED to be, dammit!"