Tribler - Privacy enhanced BitTorrent client with P2P content discovery.
transmission-telegram - Control your Transmission through a Telegram bot.
magnetico - Autonomous (self-hosted) BitTorrent DHT search engine suite.
Magnetissimo - Web application that indexes all popular torrent sites, and saves it to the local database.
torrent - Full-featured BitTorrent-client package and utilities.
libutp - uTorrent Transport Protocol library.
confluence - Torrent client as a HTTP service.
/r/trackers - Great subreddit.