Give Gnooks a try

This website will take examples of authors you love, and use them to generate suggestions for future reading.  You can also get a visual map of authors; the closer their names are to your search term, the more similar they are.

You might also like “Library Thing”

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”.

Goodreads

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.