Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices
Readwise - Effortlessly rediscover and organize your Kindle highlights
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
Clippings.io - Organize the notes you make on your Kindle
AlReader - Alreader.com - new perspective on reading e-books.
Knotes - An efficient, beautiful Kindle highlights & notes manager