I'm surprised to see that Defcon recommends the closed source uTorrent.
μTorrent is, I think, the best suggestion for a client for people who need client suggestions. (having tried a large number of very mediocre competitors, free, open, or otherwise)
I usually stick to rtorrent on the commandline, but that's a shitty suggestion for helping bring awareness to hacker issues.
1. http://bittorrent.org/ 2. http://en.wikipedia.org/wiki/Bram_Cohen