Hadley,
I, too, hate the beach ball, not just because it signifies something taking too long, but because it means nothing! What ever happened to the watch cursor? I bitched to Apple about this at WWDC two years ago. The slower your machine, the more you have to stare at the beach ball. Now that I have a MBP I can't change out the cursor (yet) because Blobber doesn't work on intel macs and seems to have disappeared. Nothing wrong with having to wait a bit at times, but having the beach ball staring you in the face is not a good thing.
What Leopard Should Fix: Part One, Kill the Spinning Ball