...mldonkey? It has support for a lot of protocols.
and if you run the mlnet executable (I'd recommend a separte directory though), you can use their web-interface, or kmldonkey to have a nice KDE window instead.
mldonkey supports kazaa (FastTrack), but also edonkey2000, openft, gnutella, opennap, and much more
Just one side back: "netstat -anpA inet" shows a lot of connections when I start mlnet, but that's a good thing if you want to download fast.