Social networks are a good thing: People can connect, communicate and share. I think the Internet and within it, the social networks, will raise a whole generation of young people who will have learned to apreciate different cultures and people from around the world.
But most of these social networks, as much as they do good, they also violate your privacy through a very clever economic and technical measure: The Like! Button.
Content producers profit from putting such buttons on their pages because it increases their audience. Users profit from it because they can share stuff more easily. And the button providers profit from it because they can track where you go, what you look at and provide targeted advertising.
Now targeted advertising and profiling is not necessarily a problem. It only becomes a problem when you can't control your profile anymore. And that is what has happened with those Like buttons: They are everywhere and you cannot opt out. Or can you?
Yes you can, even with Chromium. I am currently trying out two Chromium extensions: Ghostery and Disconnect.
They both do a similar job: They block those tracking web bugs and like buttons. Unlike the popular Firfox ShareMeNot plugin they completely remove the buttons and thus remove function. But I can accept that and share manually.