Chat about just about anything else
Facebook tracks you whether you're logged in or logged out. They even track you when you don't have an account (so called "shadow profiles"). If you don't want to be tracked by Facebook you have to block their trackers.
Yep - if you have the Ghostery extension on your browser just see who tracking you form all over - lots of site phone home to all kinds of third party entities including fb that most people are completely oblivious to.