Dijjer is a P2P HTTP cache. It is designed to do the same job as software such as BitTorrent, but unlike BitTorrent it works seamlessly through firewalls, integrates into any HTTP client, and requires no centralised "tracker".
What's new in Dijjer
Fix numerous bugs in Message filter code
Modify network join mechanism to improve network stability
Fix bug which was causing peers to become unresponsive after several hours uptime