Atil at Mozilla developed the Collusion add-on to visualize who is tracking you at every site you visit, how they talk to each other, and how the map grows out in your travels across the web
Collusion for tracking the trackers

Atil at Mozilla developed the Collusion add-on to visualize who is tracking you at every site you visit, how they talk to each other, and how the map grows out in your travels across the web