Goodreads - See what your friends are reading.
Bookself - The social reading app 📚💬
LibraryThing - A home for your books.
24-Hour Bookclub - Every few months, we pick a book and read it in one day.
BookSloth - Book Sloth lets you add books, post and see reviews as well as interact with other readers.
Four Hour Book Club - 300+ Books recommended on the Tim Ferriss Show 📚