Quote Originally Posted by fourdc View Post
Sites can borrow cookie information

How is possible that if one visits the weather channel enters his postal code to get the weather then the next site he goes to can guess his locality.

Try it some time, get the weather then visit some porn site and find out that single women in yourtown want to meet you.
Sites can definitely NOT "borrow" cookie information... that would be the opposite of all the security models that they attempt to put in place...

As Spec mentioned, generally those ads are based on Geolocation of your IP.