Mail Queue provides an easy and simple way to send email. Each email is saved and queued up either in real time or with Celery.
TeamPlay is a web app for team communication that you can run yourself! It is similar to Github's internal 'Team' app, including a free form commenting/message board and displays of recent deployments from your team.
Rocket Python is an API wrapper for Rocket.Chat. It currently only supports a few calls, but is constantly being improved.