Goodreads - See what your friends are reading.
GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
LibraryThing - A home for your books.
Kooba - An interactive graph for finding new books
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes
Read This Twice - Verified book recommendations from people we look up to