I have the 15GB and use it for file storage
If you use it on a PC you can share among many machines but if you use it on a MAC it supposedly gets sucked up into one machine and does not share well with other MACs.
If you have a PC and DON'T have a FireWire port, you'll need to buy the IDOCK for another 40 or so to interface between USB 2.0.
If you don't have a FireWire, you may want to look at the others out there. Don't get me wrong, the IPODs are pretty good... Ans the software is good too