I saw a great Talk by Eli Pariser about how Facebook and Google manipulate without consent the information you are exposed to on the internet.

It’s great if you are interested in the politics of the web and the amount of control that companies like Facebook and Google have over information that we as users freely give them, although they would palm it off by saying “it’s relevant information targeted at you.” what they are in fact doing is editing the information we are offered. The user builds the mould with their likes, dislikes, hobbies and interests and are then restricted within it.