BitTorrent is a good software. However, it is written in Python which is not familiar to most programmer, do u wanna rewrite it to Delphi component? If yes, come on, go to join us.
http://sourceforge.net/projects/delphibt/
Torrent Torque is Torrent client fully codet in Delphi. This means that the core and the GUI is programmed in Delphi.
http://sourceforge.net/projects/torrenttorque/