SSEBin

If your browser supports Server-Sent-Events, you should see a counter updating once every 2 seconds.

Though neglected by many as Websockets' halfwit cousin, Server Sent Events have a few awesome properties:

1. Parsing is built right into the browser.
2. Reconnects are handled automatically by the browser.
3. With the exception of IE, browser support is really good.
4. They're served over plain old http, so there's no need to open a separate port and/or run a separate server. (At the time of writing Heroku apps can't use Websockets, for example, but they can use SSEs just fine.) It's highly recommended, however, that you use a server that can hold open a lot of simultaneous connections. This app uses Gevent.