A while back I came across a browser extension (was available for Firefox and Chrome, maybe others) that showed you through a graphical 'node' interface how your browser session was shared with so many other servers and web services.
Unfortuneatly I have forgotten its names, and because I don't know what the correct technical terminology is, I can't find it through searching Google.
If you know of that extension, can you please share. It was very useful, because it showed which websites were particularly bad, they shared the session with like 20 or so other websites. I remember Fb and Amazon were shocking!