Slack News Feed - Get the top posts from every Slack chat you're in.
Readwise - Effortlessly rediscover and organize your Kindle highlights
Slack-News - Read news from multiple sources within Slack by just typing
Clippings.io - Organize the notes you make on your Kindle
Metachat - A news feed for unread Slack messages
Knotes - An efficient, beautiful Kindle highlights & notes manager