Facebook is notified whenever you visit one of the more than one million sites on the web that use Facebook Connect and has a history of leaking personally-identifiable info to third parties.
Turn off the flow of your data to them!
Facebook Disconnect blocks all traffic from third-party sites to Facebook servers but still lets you access Facebook itself.
Instructions: The add-on displays an icon in the location bar if a page initiates Facebook requests. You can block or unblock the requests by clicking the icon. Your preference will be remembered the next time you’re on the site.
Note about using Facebook Disconnect with other filtering add-ons like Adblock Plus: Facebook Disconnect is compatible with other filtering add-ons, but if you want Facebook Disconnect to show blocking info, uninstall then reinstall any other filtering add-ons you have (i.e., Facebook Disconnect must be added first).