GTK-Gnutella can be installed through Synaptic
Gtk-Gnutella is a reliable and efficient Gnutella client, supporting the
latest Gnutella protocol, bandwidth limitation (both incoming and outgoing)
traffic compression, and advanced search filters among other features.
The other is called Frostwire. It is just like Limewire. It is Java base and
can run slow if you do not have alot of Ram
https://help.ubuntu.com/community/FrostWire
I really do not use p2p very much any more. I just find Bit Torrent more
effective.