"FictionFinder is a project of OCLC Research that provides access to
millions of records for books, eBooks, and audio
materials identified as fiction (including novels, short stories, dramas,
and comics). "
The site includes the usual searching interface -- title author, ISBN (because everyone knows the ISBN of the book they are looking for) -- but what makes it cool is that is includes a browsing interface that lets you see titles by awards won, characters (you can find out if , like me, you are a fictional character!), genres, subjects (like 15 novels about Public Defenders), and settings (both real and imaginary).
I have a few quibbles with the system. For example, New Hampshire is a browsable setting, but you cannot narrow it down further than that, on the other hand, Hells Kitchen (a NYC neighborhood) has its own browse listing with 15 attached titles. Also, some subjects seem to be attached to titles they don't really apply to -- The Wizard of Oz doesn't come to my mind as being about "books and reading," but perhaps I need to re-read it. However, despite these limitations it seems like a good tool for finding fiction of interest to a specific reader. And once you find a title of interest you can click on the "find any edition" link at the top left of the titles page to see the libraries around the world that have the book.