One example that I think fits very well is a websocket server. As you often have a large number of clients with long-running connections and relatively low-volume bidirectional communication, a single process running react/amp can easily handle hundreds or thousands of clients.
The majority of the examples out there are indeed contrived and better suited to a queue system as you've described.
+1 to this. I like Ratchet for websockets written in PHP. One nice thing is that I can share certain things like session code between my websocket server and my backend framework. Having both be in the same language, in the same project, makes things a lot cleaner for me.
The majority of the examples out there are indeed contrived and better suited to a queue system as you've described.