Dijjer is free P2P software that dramatically reduces the bandwidth needed to host large files.
A type of distributed web cache, Dijjer nodes rely on a small number of "seed" peers, through which new Dijjer peers can assimilate into the Dijjer network. These are not essential however, you can (through use of Dijjer's command line interface) instruct Dijjer to assimilate through any Dijjer peer. You could even create a network of Dijjer nodes that is entirely separate from the main Dijjer network.
These details are provided for information only. No information here is legal advice and should not be used as such.