Debian provides many bittorrent applications:
2. Direct Connect
Check out Valknut, a nice GUI client for the Direct Connect protocol.
Another Peer2Peer application available in Debian is GNUnet which provides a fully crypted and anonymous network for Peer2Peer exchange.
4. eD2k and Kademlia
aMule is available from the Debian repositories. Built for multiple platforms and released under the GPL, amule provides an eMule like connection to the ed2k and kademlia networks. aMule provides classic GUI and optionally, a web or a terminal interface. For more information see the aMule website.
gtk-gnutella connects to the peer based gnutella network.
MLDonkey[1,2,4,5], gnutella 1 & 2, soulseek, bittorrent