datapile uses Play
Play is a central framework/component/library (not sure what to call things these days) in Scala. We <3 Scala, and therefore we <3 Play.
Play is on of several frameworks we are prototyping and vetting for various public-facing websites, and may ultimately be the framework behind the main datapile.io website.
elo80ka uses Play
I used Play to build a configuration UI for the service, which let you create and manage the menus (a hierarchical tree of options and actions).