Goodreads - See what your friends are reading.
LibraryThing - A home for your books.
MyAnimeList - Start cataloging anime you've watched or manga you've read.
Readernaut - We are a small community of readers, sharing our adventures and supporting each other as we persue a life of learning.
Riffle - Just good books and the readers who love them.
Bookicious - Find the best new book to read with books collections for makers, founders and entrepreneurs.