There was a post on ReadWriteWeb yesterday about a social networking tool called Zentact. It's a recently announced service that lets you tag people within your list of contacts with relevant terms. For example, for someone tagging me, they might use terms such as "analyst," "Burton Group," "search," and "Williams College." Then, when browsing the web, if you ran across a page that discussed Burton Group, Zentact would notify you and make it easy to send a quick note saying, "Thought you might find this interesting." The pitch is that it "transforms contacts into relationships."
The service strikes me as useful if used with restraint; I'm worried that it will become popular within the PR community and that my Inbox will get filled with even more drivel. Time will tell....