HeySpace - HeySpace is the only free task and simple project management software with communication and collaboration feature.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
Slack - A messaging app for teams who see through the Earth!
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.
Skarpline - Skarpline provides centralized enterprise messaging, link sharing and file management to improve productivity.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.