Here is a neat little application that will check your privacy settings for you. It takes about 2 minutes and will let you know where your security weaknesses are. Take a minute and check it… please. For your sake, not mine.
http://www.reclaimprivacy.org/facebook
And another tool is the Facebook Sanitiser, which does a lot of the work for you… but I prefer the first link.
http://facebooksanitizer.com/
