What's cool for me as an author is that it also aggregates and displays data across all my books. Now... my books are not exactly NY Times Bestsellers (what? you mean the world isn't racing to learn about UC security? :-) so the data isn't as exciting as it would be for those with more mainstream books... but it's very cool to see. Thanks to Amazon for making this data available (for free) to all of us who write books!