Speaking with a potential Chapel user today, they indicated their appreciation of the Go playground: Specifically, that they could be reading some documentation, click on an example, have it appear in the playground, and run it—the implication being "it sure would be nice if Chapel could do this as well."
One approach to this would be to potentially leverage ATO as our playground and have a way of either having code links populate an ATO session, or a script that creates ATO URLs from code snippets.