http://www.nytimes.com/2012/02/05/opinion/sunday/facebook-is-using-you.h...
So basically this news article is how both facebook and google track your history to come up with ads that are relevant to you. Google tracks what you wrote in previous emails and previous google searches... how creepy! Basically you have no privacy! Yeah I like the personalized ads, but I don't like how my emails and facebooks posts are being tracked.