Ghostery is a free privacy browser extension for Internet Explorer, Opera, Mozilla Firefox, Apple Safari, and Google Chrome. It enables its users to easily detect and block web bugs, that are objects embedded in a web page, invisible to the user, that allow the collection of data on the user’s browsing habits.
Ghostery sees the invisible web – tags, web bugs, pixels and beacons – and tracks the trackers, giving you a roll-call of the ad networks, behavioural data providers, web publishers, and other companies interested in your activity. It allows you to block scripts from companies that you don’t trust, delete local shared objects, and even block images and iframes.
You can get Ghostery here: http://www.ghostery.com/