Congratulations, you just missed the entire point of having a 68k Mac Liberation Army. 68k Macs? I don't think you can get more obsolete. Yet, time and again, our users prove that they have at least some use, whether in furtherance of nostalgia (Dark Castle!), in a productive capacity (MacWrite is a damn good distraction-free environment for novelists, or so I'm told), or even to do entirely new things with (macbsd/68k would be a good example).
PPC Macs are surely less "obsolete" than their 68k brethren, so why would we think them any less valuable?
That said, you've got a 17" PowerBook G4. The best use of it would be to plonk down Tiger or Leopard (I vote Leopard myself) and enjoy the ride.