Wikipedia
EXeem
eXeem was a peer-to-peer (P2P) file sharing client using the BitTorrent protocol. eXeem was designed to replace the need for centralized trackers (servers which co-ordinate the transfer of metadata across a BitTorrent network). It largely failed to achieve this goal, and the project was canceled and eXeem's network was shut down by the end of 2005.
eXeem was written in C++ using the open source libtorrent library for its bittorrent functionality.