The stock quote and hangman plugins are really just demos. Where services like this really shine is when you integrate them with your existing systems. Starting a Jenkins build from your Slack channel is pretty nifty.
But this would need setting up to interact with Jenkins? Assuming yes, at that point, why not just hop on over to the Slack App Directory and pick up something there?
e.g. https://slack.com/apps/A0F7VRFKN-jenkins-ci