Actually, that reminds of the Freedombox. Are you familiar with it? It's a software stack that's supposed to run on a plug computer and provides various services (email, blog, social network) in a privacy-respecting way (distributed, versioned, encrypted back ups, etc). One cool proposal they came up with was in backing up PGP private keys securely. You could select say 5 or 6 (or 20 or 50) trusted friends and send each of them pieces of your private key. They would all have to collude to pwn you, which presumably they wouldn't because you selected people you could trust. If you lost your key, then you contact them, and after they verified who are you, you could reconstitute your private key. Voila! Distributed trust. That would be more difficult in a truly anonymous network, but it sounds similar to what you were saying. I know you were talking about the web of trust model.