Collusion is a plug in for Mozilla Firefox. It tracks and graphs what's leaving tracking cookies on your system while browsing the web. It does a good job at representing the connection between all the sites that track your online browsing and the fact that everything you do on the web is tracked by someone, whether that be for profit or not.
Who you think is tracking you:
Who is actually tracking you:
There was a Ted Talk introduction done by Gary Kovacs CEO of the Mozilla Corp., called "Tracking the trackers." Have a look:
Interesting food for thought regarding what you do online.