It turns out Facebook saves everything you do, even if you never post it,
even if you delete it. They're spying on you and tracking what you do at a
level even beyond Google. Makes you wonder what they're doing with that
information:
http://www.latimes.com/business/technology/la-fi-tn-facebook-can-track-users-unpublished-posts-20131217,0,7847582.story
