Taskade - Make lists, organize your thoughts, and be inspired to get things done. Taskade is a collaborative space for your tasks.
Slack - A messaging app for teams who see through the Earth!
The New Dropbox - Enterprise software portal for team collaboration
9mCollab - Collaborate (efficiently) Conclude (fast) Contribute (in the knowledge base)
P2 - Share, discuss, and collab with your team. By Wordpress.
Mattermost - Mattermost is an open source alternative to Slack.