A free and reliable P2P BitTorrent client
An advanced and multi-platform BitTorrent client with a nice Qt user interface as well as a Web UI for remote control and an integrated search engine. qBittorrent aims to meet the needs of most users while using as little CPU and memory as possible.
LeechCraft is a cross-platform modular "internet-client" application. It has plugins that allow one to browse the web, chat via instant messaging (like Jabber or IRC), read RSS/Atom feeds, download files via BitTorrent, Direct Connect and other protocols, play media files and much more.
GTK-based BitTorrent client. You can find Ubuntu packages of Flush at http://bit.ly/cYBYQf. Git repository: http://bit.ly/cdwdPE.