I have created a newer version of MMM-Slack which I have called MMM-Slack2. I wrote this module because of the changing API of Slack.
Until now, the events API has not been implemented yet, so the module will not immediately refresh when a new message has been sent to the channel. It only gets new messages periodically. A guide on how to use the module can be found on github.
I use this module to have a simple way to display messages in a house so that they can be read without having to use a smartphone.
Feel free to try out the module and send me your feedback. If you have any ideas for new features or if you can help implement the Events-API, please contact me