Some of you might know that I have a library for encoding PHP variables to their BitTorrent counterparts, and back to PHP, called PHP BitTorrent. Some days back I pushed another library to GitHub, namely a standalone BitTorrent tracker.
The tracker is pretty extensible and comes with a couple of back end implementations for you to choose from, the default being MongoDB. The tracker is not a complete tracker system with user authentication and torrent downloads and such, but a standalone “announcer” (like for instance the official BitTorrent tracker: bttrack). PHP BitTorrent Tracker can easily be extended to do user statistics and so forth though. An event listener doing this is shipped with the package.
More information (installation, configuration and more) is available at the project page on GitHub. Feel free to play around with it, and please use the issue tracker at GitHub if you find any issues. Happy torrenting!