Public - Group chats.
Teachable - Create and sell beautiful online courses with the platform used by the best online entrepreneurs to sell $100m+ to over 4 million students worldwide.
chitchat - Chat Room with Selfies and Pagers (yes, pagers!)
Clever - syncing between education applications for K-12 schools
Slack - A messaging app for teams who see through the Earth!
Claroline - Claroline is a collaborative eLearning and eWorking platform.