Gnucleus is a p2p (peer to peer) file sharing application for Microsoft Windows. It is released under the GNU General Public Licence which means it is free (as in speech) software. The underlying protocol for seaching files is the Gnutella p2p network.
Gnucleus supports all the latest features of the Gnutella protocol including ultrapeers, SHA-1 file hashing, download swarming. It is completely spyware and adware free. Since it is created in peoples spare time, it does have a couple of bugs. They are usually merely a minor nuisance though. It is still one of the most effective Gnutella clients around.
Other good clients for the Gnutella network include BearShare and LimeWire. The latest edition of the Morpheus file sharing application is actually a fork of Gnucleus with added ads and spyware.
The Gnucleus Website is: