Build a simple Slack app that sends one-way messages to a channel using a Node script.
When another website is doing the heavy-lifting updating some content you want to keep up on, but there's no good integration with Slack, you can parse it yourself and post directly to a Slack channel.
Once you learn how to use Slack's incoming webhooks, the possibilities are endless. See how to post to Slack using Ruby.
Post a message to one of your Slack channels when your Rails app encounters a 500 error.