Papermind - Papermind Slack App is a collaborative article-editing and document management platform for Slack

Slack - A messaging app for teams who see through the Earth!

Trainual + Slack Integration - Capture knowledge or access training right inside Slack

Flow - Stop managing projects from your inbox.

Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates

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.