Goodreads - See what your friends are reading.
Commit Together by Github - Now add co-authors to your commits
LibraryThing - A home for your books.
Commit Print - Posters of your git history
GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
gitbird - So, I don't always remember to tweet what I do, but commit my code often, and what do users love more than your product?