Azureus is a Java-based BitTorrent client that has a big following on both the Mac and Windows. Unlike BitTorrent OSX and Transmission, it has features coming out of its ears. It offers three user levels: beginner, intermediate and advanced. Beginner is suitable for normal torrent use, while the intermediate and advanced levels provide full torrent-tracker server features, character set decoding, MTU packet control and other esoterica. Even at the beginner level, which is recommended for most users, you're given a great deal of control over torrent management, as well as almost alarmingly exhaustive statistical details. If you want to see a graphical representation of the data blocks being acquired and assembled, Azureus can show it. It's also the only Mac BitTorrent client that allows selective downloading of files within a torrent. Its interface is certainly not as nice as Transmission's, but it feels altogether more powerful.
