Facebook is rapidly taking over the planet, and Drupal is arguably trying to do the same. Facebook added the concept of 'liking' a webpage to their array of social tools a while ago. Drupal modules quickly added the ability to 'like' content on your site.
This is all well and good, but what about getting some of that data back into Drupal?
Suppose that you have an image gallery, and you want people to be able to rate the images, by 'liking' them using Facebook like. What you'd really like to be able to do then is build a 'top rated' view of those images.