Goodreads - See what your friends are reading.
GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
Bookicious - Find the best new book to read with books collections for makers, founders and entrepreneurs.
Oku - Track your book lists and get recs from your friends
Bookcelerator - A curated directory of books that will make you smarter
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes