Whether your Facebook profile is perfectly tailored to reflect everything you care about in life, or just has a picture from five years ago and a made-up name, you give the world some detailed insight into your personality through what you slap on that page. When you meet someone new, what's the first thing you do to really see what they're all about? You Facebook stalk them.
Now, researchers at the University of Cambridge have gone even deeper than just a surface glance, in their quest to understand peoples' psycho-demographic profiles, and they've harnessed the power of the 'Book, which is, once you think about it, the largest cache of individuals' likes and preferences ever assembled. They've compiled an immense database of information from peoples' profiles (with promises not to share any of it, of course) to establish population percentiles of various personality traits and the types of people they belong to.
Once you sync your profile to the tool, it can tell you things like how happy, intelligent, and even neurotic, you are compared to the rest of the population.