Attached is an example of AJAX.NET 2.0 chat which stores the chat info in the sql server database.
It is separated into two projects, one class library for the chat operations, and one asp.net 2.0 site for the chat interface.
I did this, because since this is my first AJAX.NET application, i did not want to get mixed on what part is giving me the trouble in case of a failure or an exception. This way, I can test my chat app and ajax separately.
It is not fully completed yet, but I will keep updating this.
And I need to find a way to put the mdf file here as well :)
Notes : I have updated the attachment, added a DB project to the solution, so that you can create the tables yourself, and on any SQL db you like.
Also the Chat Folder requires authentication, but you can choose how you authenticate, i am using the ASP.NET 2.0 DB for all.