Frostwire from Get-deb.net does Limewire. You can also get Limewire itself from
their site. Amule (repositories) does eDonkey. GTK-Gnutella (repositories) works
on Gnutella. There are some Napster ones and several other specialty ones that I
have never used. Also there are lots of torrent apps. Transmission comes with
Gnome, but I prefer Deluge.