BitTorrent is a tool for copying files from one machine to another. FTP punishes sites for being popular. Since all uploading is done from one place, a popular site needs big iron and big bandwidth. With BitTorrent, clients automatically mirror files they download, making the publisher's burden almost nothing.
Coherence is a set of DLNA/UPnP devices, like MediaServer and MediaRenderer. In addition, it includes a well-designed framework to extend other applications with DLNA/UPnP functionality. It also has an emerging DBus API, enabling these applications to participate in digital living networks. It supports Playstation 3 (PS3), XBox, and many other devices.