Readernaut - We are a small community of readers, sharing our adventures and supporting each other as we persue a life of learning.
GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
LibraryThing - A home for your books.
Goodreads - See what your friends are reading.
Read This Twice - Verified book recommendations from people we look up to
aNobii - aNobii is a social network for listing books, sharing insights, and meeting people.