“Dijjer is free P2P software that dramatically reduces the bandwidth needed to host large files. […] You don't need to install anything. Just put a file on your site as you normally do, but add "http://www.dijjer.org/get/" to the beginning of your links:

normal link: http://mysite.com/video.mov
dijjer link: http://dijjer.org/get/http://mysite.com/video.mov

[…] Dijjer source code is released under the Gnu Public License (GPL).”

dijjer.org WritTorrent