Pretty much everyone agrees that Gravatar rocks. A global avatar that shows up wherever you make a comment on a blog (sometimes even in your desktop apps). And I don’t think anyone other than naive VC guys wants another “social networking” site, so I’m not going there. But, imagine what would happen if every time you made a comment on a blog that used Gravatars a ping was sent off to the “Gravanetric” servers with two bits of information the hash of your e-mail and the root url of the site you posted too.