Look, its really simple. If you don't want them tracking you and sending you emails and such, do not sign in to things like Google. I don't know if people realize this, but if you use search engines like Google or Yahoo, make sure you DO NOT sign in if you don't want your history being known.
In any case, like Wolfman said, there is pretty much no privacy online anymore. As soon as you logged on to websites like Facebook and such, forget privacy.