qBittorrent - Lightweight and open source torrent client that runs on all major platforms.
dottorrent-gui - An advanced GUI torrent file creator with batch functionality, powered by PyQt and dottorrent.
Deluge - Deluge is a full-featured BitTorrent client for Linux, Unix and Windows.
Torrent File Editor - Qt based GUI tool designed to create and edit .torrent files.
rTorrent - rtorrent is a BitTorrent client for ncurses, using the libtorrent library.
JSTorrent - Torrent client for Google Chrome and Chromebooks