Deluge
From Cubits homepage (http://www.cs.cornell.edu/~bwong/cubit/index.html):
"What is it?
Cubit is a system that provides fully decentralized approximate keyword search capabilities to Azureus as a standard plugin. Approximate search means that you can use Cubit to find a movie, song or artist even if you don't know which spelling variation is used in the title or in her name. It gives you what you mean instead of what you asked for exactly, and returns the best results in the network in only a few seconds. "
Slashdot got a story on this today, about how this could be a possible solution of TPB really does go down. Since the code is open-source and licensed under GPLv2, could someone port it over to Deluge?
You can download it here: http://www.cs.cornell.edu/~bwong/cubit/download.html