Alcamy - Free, open self-learning platform. Learn & teach anything.
Goodreads - See what your friends are reading.
4books - Learn the key ideas of the best business books
LibraryThing - A home for your books.
StackML - Machine Learning platform in-browser, for creators
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes