Take a look at the Literature Map
If you put in an author you enjoy, a web of similar authors will magically appear. They are arranged so that the closer their style of writing, the closer together they will be on the web. Below you can see what I got when I searched “Margaret Atwood”.
A book recommendation site, but again, it will make suggestions based on what you already like. You can build a virtual “shelf” of books you own or have already read, and also connect with other readers to share suggestions and reviews.