ZeroMQ usage in web application: how frontend interacts with backend
The easiest way to do this is to map WebSockets to ZeroMQ sockets, which is quite simple with tornado and PyZMQ's ZMQStream objects. An example of such an app is the IPython Notebook. This approach has the downside of requiring websockets, which puts a limit on what browsers you can support. Of course, you could also map ajax calls with jQuery, etc. and handle the relay with async handlers in tornado.
A more sophisticated web:ZeroMQ app is the mongrel2 webserver.
The right choice for you is just going to depend on your communication patterns.