HackerWeb - A simple and readable Hacker News app
Readwise - Effortlessly rediscover and organize your Kindle highlights
HNwatcher - Track keywords and users on Hacker News
Clippings.io - Organize the notes you make on your Kindle
Hacker News Stack - Focus on the really fresh and unread news in Hacker News.
Knotes - An efficient, beautiful Kindle highlights & notes manager