[icebraining]

What you're describing is similar to a darknet like WASTE or Freenet; they connect to friends and store-and-forward the content as requested.

As for UID, if you just want some kind of unique identifier, you can just use a public RSA key. If you want an unique but readable name (like a nickname), you need something more sofisticated. A possible approach is Namecoin's, which tries to guarantee unique but decentralized domains.