Holy fuck, that freaked me the fuck out haha. That's hectic how that website is able to do something like that, and it really makes you think that something like that could be happening right now somewhere around the world. You give out the slightest bit of personal information and some freak could be able to track you down using it.
That's why I like Facebook's new privacy settings. The only people I have as friends are people I know in real life or at least grew up with or know of from school. Anybody that isn't my Facebook friend will only see my profile picture, but even then you'd need to put the face to my exact location, which is surely quite tough to do for somebody not associated with something like the F.B.I or whatever.