Is there an IMDB.com-type welsite for the book world?

You can try the Internet Book List, although currently the content on there isn’t great.

I often use sites like Wikipedia and Amazon for info about books.

Wikipedia is particularly good. But there isn’t a particularly good dedicated resource that I’m aware of.

I have not found a good single resource either. For current books, I use Amazon a lot. I get some details like plot synopses, sometimes a peek at pages, author and publisher info, etc. For mysteries, this one is a favorite site of mine: www.mysteriousbookshop.com. IF you know the author, nowadays many have their own web sites. I use those a lot.

I don’t know of one website. My first thought was the Library of Congress which seems difficult to use. There is a website called Allbooks.com which classifies books by character, plot, setting, and writing style. The NY Times Book Review would be a good source. You must register to use this site. Hope this helps.