Blocking FacebookI'm not a big fan of giving away information, particularly to large corporations that have loose privacy policies, so I do what I can to prevent this kind of tracking. Step one in this case is always logging out of facebook when I'm done with a session (I've largely stopped posting to facebook anyways), but I've also gone the extra step and added it to my firefox ad blocking plugin. The ad blocker works by filtering out a list predefined URLs in an HTML document that refer to ads, the net result is an ad-free web browsing experience.
Adding *facebook* to the list of URLs enables me to ultimately block any communication with facebook servers unless I explicitly allow it. I suppose this technique could be used for any website.