When it comes to Linux, I usually just use the command line for BitTorrent. If I actually download the .torrent file, I use this:
btdownloadcurses --max_upload_rate 350 --responsefile blah-blah-blah.torrent
If I instead have a URL, I use this:
btdownloadcurses --max_upload_rate 350 --url http://domain-name-and-path-to-torrent
Otherwise I use Azureus. If I'm on Windows, I usually use uTorrent, which is small, fast, & powerful. But there are lots of options, and Michael Calore at Webmonkey reviews several in his "BitTorrent Client Shootout", including some of the ones I mentioned. If you're interested in variety, check it out. It's an easy and informative read.
(Check out all of our posts on BitTorrent, Azureus, and uTorrent.)

1. BitTornado is awesome as a Torrent manager. I've actually been a bigger fan of btdownloadgui instead of btdownloadcurses, mostly because I never use anything but the web to find torrents. For instance, my copy of "The Best of Blondie" had a run in with my dog right before I got to that stack of cds while archiving, so I went out to a torrent site, and downloaded the .torrent file, and then opened it with btdownloadgui and watched the whole thing go. No Windows box connected to the internet, so I don't know about the dark side of torrents...
Posted at 7:23PM on Apr 5th 2006 by Paul