"Ghostery is your window into the invisible web – tags, web bugs, pixels and beacons that are included on web pages in order to get an idea of your online behavior. Ghostery tracks over 1,200 trackers and gives you a roll-call of the ad networks, behavioral data providers, web publishers, and other companies interested in your activity."
I can't believe I didn't bookrmark this before. In any case, it's relaunched with a bunch of new features.
