Book database websites

I need a website similar to IMDb that lists books and their series. I just want to know, when I look up a book, what series it belongs to and in what position it sits, plus what other books are in that series. I'm certain there is something like that, but I don't know what it is.

I found some suggestions from forums via a Google search and narrowed it down to:

http://www.goodreads.com/
http://www.librarything.com/

A lot of them have the same or similar information, so it's really down to usability. One site had Next and Previous links for navigating within a series, but no overall series summary page with links to each book. Some put too much emphasis on the social media aspect, which naturally de-emphasises the book info database. Some focus too much on shopping for books rather than finding information about them. These two, however, had pretty much exactly what I was looking for.

Mokalus of Borg

PS - Now it's just a question of which URL is more memorable.
PPS - Or which site is more usable, which might be LibraryThing.