Some people have been asking me about rtorrent and where to get it for the Mac. It's in both fink and MacPorts, but if you think that installing a whole package management stack is a bit overkill for a nice BitTorrent client, I've compiled an internet-ready (yay!) DMG using MacPorts. You can download it from here.
At 6.8MB it includes a lot of stuff you would normally never need, like the header files of libtorrent and all support libraries. The binary is placed in /opt/local/bin. Intel-only.