Facebook applications allow users to involve other users in games. What most users do not realize is when you agree to use an application it gives the owners of that application permission to view your personal data. This has led to several news stories of abuse of private information. As a user, you have little recourse because you gave them permission when you pressed the button!
Look at the image above. By agreeing to participate in the application, I give permission to 1) Access my information at any time including my friends! 2) obtain my email address and send me mail (or SPAM) 3) Post whatever it likes on my wall! Way too much permission for me to trust.
Use Facebook if you choose. But stay away from those applications. They are more than time wasters, they are privacy destroyers. Don’t put anything in Facebook you don’t mind being public, because it one day will be. Your private information is being captured, stored, and in some cases, sold.