A Greasemonkey script to help you find your friends' profiles. Built at Open Hack London 2009
If you have Greasemonkey installed, just go to this URL: georgebrock.com/openhack2009/xfndiscovery.user.js
Once the user script is installed, when you visit a page that contains any rel=me
links (a Twitter profile, for example) a link will appear in the top right corner of the page that gives you access to any other profiles the user might have online.
There is a Greasemonkey-like plugin for Safari called Greasekit. Unfortunately this plugin isn't currently compatible with Greasekit. It might be one day, but no promises.