Ktorrent
KTorrent is the BitTorrent client for KDE.
Installation
Troubleshooting
Unable to see some bottom panel tools
To be able to show any information about the files, seeders, leechers and the current trackers, install the optional dependency geoip. It is advised to enable DHT inside the Settings to avoid slow speeds and low amount of seeders.
Script to manage it in command line
Since KTorrent is a GUI only application, it fortunately has a DBUS interface, so you can use scripts to manage it in command line (i.e. from SSH). See the following linuxquestions forum answer for details.