On Slack by Standuply - The most extensive book on using Slack to the utmost
Slack - A messaging app for teams who see through the Earth!
Startup Playbook by Hatch Quarter - A guide to building your startup
Standuply - Run daily standup meetings and track your metrics in Slack
Marketing for Startups - 47 practical tactics to get customers and achieve hockey stick growth.
Glide 3 - Lightning fast live video messaging