Right now I have some code started for a bookmarklet that runs on Facebook and scans some of the most common privacy holes that are enabled by default. It shows a summary and has "one-click fixes" to lock down those privacy settings. Check it out here:
http://www.reclaimprivacy.org
I started this project last weekend on my flight back from Michigan to the Bay, and I just don't have enough free time to really make it solid. The bookmarklet needs better cross-browser testing (I works well in Safari 4, and mostly okay in FF3), and there are plenty of important privacy checks that it still needs to do (wall-post privacy settings, photo privacy settings, etc). A few of the checks can be wonky at times, especially the ones that scan the privacy dropdowns.
So...join in! If you want to contribute, just fork it on GitHub:
http://github.com/mjpizz/reclaimprivacy
...I'll check pull requests periodically and redeploy the latest patches. The project is contained in an AppEngine app since that was the easiest thing to throw up on a Google domain this morning.