It's a Literature Map. You go on the site, type in the name of an author, click continue. The map that pops up lists authors that have similar writing to that of whom you typed in. From the site: 'The closer two writers are, the more likely someone will like both of them.' Then you can click on the other authors to see what their map looks like.
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I can't speak to it's accuracy, but it sure is fun to play with! What do you think?
(click the image for the site I found it on: Exocubic Studio. This was the designer's sketch for a book mobile he made for a library in Little Rock, AR. Beautiful, isn't it?)