PeerBuddy is a P2P application that attempts to share files based on hash IDs used to track portions of a file. This can be used to find replacements by skipping parts of an incomplete file and downloading only the missing portion.
Other future possibilities include blocking files and banning users based on file content instead of names or IPs (although IPs can be banned as well). Even if the main servers went down, and the program had no IPs, it can still find other clients to search.
