Firefox 4 and Chrome 6 have support for Websockets.
This tool is a Websocket server, that forwards Recent Changes from IRC to a web browser, in order to visualize them dynamically.
It runs on port 9999. The server status can be checked here
(the "load" is an average, expressed in messages per second)
Here is a list of pages using it:
If you decide to write another page that uses this server, please add it to the list.
It is possible to use this tool directly on any Wikimedia wiki ; here is a script that turns the RC page into a self-updating page:
category:Tools by ThomasV