Hacker News Stack - Focus on the really fresh and unread news in Hacker News.
Knotes - An efficient, beautiful Kindle highlights & notes manager
Hacker News Front Page Explorer - A database of top ranking Hacker News front page posts
Readwise - Effortlessly rediscover and organize your Kindle highlights
Box Piper Hacker News - Re-Imagined Hacker News for this decade.
Klib - Kindle & iBooks Highlights Manager