Goodreads - See what your friends are reading.
Literal - Track your reading and discover your next favourite book
Readernaut - We are a small community of readers, sharing our adventures and supporting each other as we persue a life of learning.
Readup - Track and improve your online reading habits.
aNobii - aNobii is a social network for listing books, sharing insights, and meeting people.
Bookling - Track your reading habits and set goals