In the olden days a sociologist had to find people and recruit them to fill out long arduous forms. Today there is Facebook, and these sociologists are finding out that people generally love to talk about themselves. It is fun to talk about my interests, social networks and life!
Check out the New York Times article ‘On Facebook, Scholars Link Up With Data’. I would imagine this is being used in many other ways and will be being used more frequently in the future.