Transmission is a fast, easy, and free multi-platform BitTorrent client with a focus on being lightweight yet feature-filled.
Today Transmission finally came out of beta with the release of version 1.0.
Version 1.00 Features: All Platforms: + Port forwarding now performed by MiniUPnP and libnatpmp + Ability to set global and per-torrent number of connections + Option to prefer not using encryption + PEX is now configured globally + Updated icon OS X: + Redesigned Leopard-like look + Group labeling, filtering, and sorting + Statistics window + Pieces Bar (return of Advanced Bar) + Display "not available" overlay on the regular bar + Display remaining time for seeding transfers + Sort by total activity + Connectable from the Clutch web interface + Leopard: Time Machine will ignore incomplete downloads + Leopard: Fix bug where text fields would reject localized decimal values + Leopard: Fix bug where bandwidth rates chosen from the action menu would not apply the first time GTK+: + Redesigned main window interface + Minimal Mode for showing more torrents in less desktop space + Torrent filtering + Port forwarding tester in Preferences + Statistics window + Sort by total activity, progress, state, and tracker + Various other interface additions and improvements CLI: + Restore `scrape` feature