Right now I play a little bit with Maven Central repository index and try to get something interesting out. For the moment I'm sorting data and creating statistics. First of all I wanted to find out how many libraries are in the Central repository. Website http://mvnrepository.com/ in the top left corner has a chart which shows just that, but I never believed it, because it looks so unreal. But it's true, currently there are almost one million artifacts (just libraries without sources and javadoc).
Btw. I used these projects to get the data out: