FACEBOOK is at the top of that list. And they won’t think twice about giving out user’s privacy details.
Btw, I think users need to know that there’re a few things to consider before signing up with a username since you can’t change it.

Yeah, we somewhat "agree" to take it up the ass by registering so they can do whatever they want with our content. It boils down to the company's ethics (and staffs) in the end.