Documize - Enterprise-grade wiki and knowledge management platform
Slack - A messaging app for teams who see through the Earth!
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
9mCollab - Collaborate (efficiently) Conclude (fast) Contribute (in the knowledge base)
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
IntouchApp - Universal contacts manager for mobile.