about tracking by some addons by collecting visited sites url,ip etc
in review of some addons user suggest to not to use that addon because that addon track you.
is this may be harmful us if some addon track us ,some lines from privacy police is following
<In the course of using our site, we automatically track certain information about your online activity. This information includes the URLs you go to, what browser you are using, and your Internet Protocol (IP) address. We use your IP address to help diagnose problems with our application and to gather broad demographic information.>