I came across the most novel UI for a file sharing application.
Minitasking.
It allows you to find and download music or movies from gnutella, using a visual medium. The bigger a blip the bigger the ammount of files its holding.
Random file names are what others are searching. Right clicking any where in the view pane, will allow you type in a search term.
You can grab Minitasking at
http://www.minitasking.com/
Its free, and by that I also mean spyware free.
I think more people developing p2p apps should look to diffrent ways of representing a UI.
Minitasking is a bet heavy on the cpu though, so a fast machine is a must.
Here is how things looked for my search of "madonna"...