Mirro - An all-in-one team performance management solution made easy
Skype for Slack - Move your slack discussions to a group skype call
Tettra - Tettra is a company wiki that helps teams manage and share organizational knowledge.
Calls on Slack - Make voice calls in Slack
Charte - Free online interactive charts for non-techies
Pingly - Your communication hub — Email, text & voice in one app