Twist - Check fewer notifications, do more meaningful work. Twist is the team communication app for calmer, more organized, and more productive teamwork.
Slack - A messaging app for teams who see through the Earth!
P2 - Share, discuss, and collab with your team. By Wordpress.
9mCollab - Collaborate (efficiently) Conclude (fast) Contribute (in the knowledge base)
Wait.chat - Deadline-aware message inbox for async teams
IntouchApp - Universal contacts manager for mobile.