simple extension to email that lets you append your entire address book to outgoing mail message without compromising your privacy. Correspondents can use this information to prioritize their mail, and learn more about their social networks.
Li Fan, Pei Cao and Jussara Almeida & Andrei Z. Broder - this new protocol, each proxy keeps a summary of the cache directory of each participating proxy, and checks these summaries for potential hits before sending any queries.