Privacyfix is an add-on for Mozilla's Firefox browser that lets you see and control what information of yours is being tracked on the web.
Advertisers see a lot of information about your interests based on what's available publicly in social spaces like Facebook. If you think your information is secure, think again. Use Privacyfix to see just what's available for public viewing by advertisers.
Privacyfix is easy to install, and will immediately show you what bits of your information are viewable by third party advertisers, as well as let you tweak settings accordingly. It immediately checks accounts you're already logged into on Firefox. For more options, it will prompt you to log into your other various accounts.
Privacyfix can check Facebook (plus the various apps you have installed) and Google, as well as websites you frequently visit. By using a convenient web-based interface, you can toggle between options in the upper bar, then pick and choose what settings to fix in a righthand column below.
Generally, Privacyfix will send you into a new tab to change Facebook settings, and some users might notice a few bugs that need working out with the add-on. Most specifically, the add-on seems to confuse the custom post option on Facebook with the public posting option.
If you're concerned about your information's security online, Privacyfix is a great way to monitor and tweak it.