BitTorrent
http://www.versiontracker.com/dyn/moreinfo/macosx/18286

Tomato Torrent
http://www.versiontracker.com/dyn/moreinfo/macosx/22891

Azureus BitTorrent Client
http://www.versiontracker.com/dyn/moreinfo/macosx/22820

Bits on Wheels
http://www.bitsonwheels.com/