Made an account just to comment: Goodreads seems to be way more interested in selling books than recommending books, and they want to sell books from Amazon primarily, then other major online retailers. I'll give points for including "smaller" retailers like Indiebound, but they're at the bottom of the list.

I just switched to LibraryThing and I'm in love with it. It not only predates Goodreads but it runs circles around it. Go to a book page on LibraryThing and you're treated to the most common tags for it, people with similar libraries to yours who have it in their libraries, member recommendations for similar books, lists the book appears on, forum conversations, and a full list of translators, editors, and illustrators. Want to acquire the book somehow? You can configure LibraryThing to have links to major retailers and even search for local book shops and libraries and have them appear in all book pages. AND, if you want to swap a book for another book instead, it gives you links to swap sites with how many are available and how many are requesting said book.