Readwise - Effortlessly rediscover and organize your Kindle highlights
GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
Knotes - An efficient, beautiful Kindle highlights & notes manager
BookAuthority - BookAuthority collects the most recommended books on business, technology and science - as featured on CNN, Inc and Forbes
Clippings.io - Organize the notes you make on your Kindle
Goodreads - See what your friends are reading.