#SMSBoard
SMSBoard is a text-messaged powered message board. It works out of the box with Nexmo and Heroku, but can easily be adapted for other APIs and services. This also requires a Redis instance (even the lowest tier on Heroku will work).
This app uses websockets, so messages sent to the phone number will appear instantly. It also uses push notifications to alert the user that a new message was sent. None of the data is stored between sessions.