Suggestions for creating a good chat application with comet

I am trying to build a chat application using c# asp.net ajax javascript. I heard about comet and 开发者_JAVA技巧people say that you can build a first class chat application. Does anyone know any good tutorials on making a full built chat system in a website (using comet or not)?

A blog post that I wrote some time ago (http://kboek.blogspot.com/2009/09/using-ihttpasynchandler-and.html) might give you some ideas.

Here's a start: http://www.frozenmountain.com/websync/learn/demos/extjschat