I have some reservations about this web site, but it is definitely one worth knowing about
:
http://www.literature-map.com/
The idea with the above is that you put in the name of an author you like, it it will give you others that are allegedly similar. Another one in this ballpark, but IMHO not as good, is similarauthors.com.
The problem I find with this kind of site is that without knowing why I typed in an author, they don't have a clue what to return. For example, say someone puts in Faye Kellerman. I could be looking for:
-- Novels with an Orthodox Jewish setting
-- Novels set in Los Angeles
-- Police procedurals
-- Long ongoing series that started being published in recent decades
-- Husband/wife mystery series
-- Bestsellers with traditional values
-- Novels about adopted people
-- A long series of novels where every book is available as an OverDrive eBook
etc., etc., etc. And most of the above does not seem to be a consideration in who they recommend.
Despite weaknesses, I do like literature-map.com.