Still, it's an honor system, says Adrienne Felt, a computer science major at the University of Virginia. A Facebook user herself, she decided to research the site's applications and even created her own so she could see how it worked.

How much is too much?

Most of the developers Felt polled said they either didn't need or use the information available to them and, if they did, accessed it only for advertising purposes.

But, in the end, Felt says there's really nothing stopping them from matching profile information with public records. It also could be sold or stolen. And all of that could lead to serious matters such as identity theft.

''People seem to have this idea that, when you put something on the Internet, there should be some privacy model out there - that there's somebody out there that's enforcing good manners. But that's not true,'' Felt says.

Know your applications:

Last year, Facebook users revolted when the company started using a tool called Beacon, which tracked its users' purchases and actions at dozens of Web sites and then broadcast the data on the pages of the users' friends.

Beacon has since been scaled back.

By comparison, the issue of personal information going to application developers, both on Facebook and now MySpace, has remained relatively quiet.