You have no idea what to read next or do you want to find an author that is quite similar to one of your favourites? Then I have an interesting website for you:
It's quite simple. Just type in the name of an author you really like and the website presents you a map of names. The farther away an authors name is, the less they have in common. And, of course, the closer they are, the more similar are their books and themes they write about.
Have fun exploring :)
(btw. this website also offers this for music and movies)