Nice job and congratulations on your progress. Now, what would be really interesting is if you were to add a WebSocket layer into the server, so one could write a browser-based client that would directly interface with the IRC server without having to proxy like mibbit does.
Yeah, I actually thought about that. I'm not sure if I want to bundle that into the main server. I made a web-based chat system maybe a year ago called JsChat, so I might use some of the stuff I learned there and do a nice Socket.IO thing.
It's not IRC per se but it's a simple enough example of realtime chat via socket.io.