If you want to know what data you’re sharing — without (thus far) knowing about it — on Facebook, ISharedWhat.com is the way. You run it as a simulator and what’s what.
It was developed by Joe Andrieu, a stalwart contributor of wisdom and code to the VRM community, and has been covered by Read Write Web and tweeted by the Wall Street Journal’s @WhatTheyKnow.
It’s what we call a fourth party app, meaning it performs as an instrument of your intentions, rather than a seller’s or a site operator’s. Check it out and give Joe feedback.