Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
Lurchr - Saves all your Slack links, so you can focus on work
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Slack News Feed - Get the top posts from every Slack chat you're in.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.