Jeremy Keith presented something regarding AJAX at XTECH 2006 entitled HIJAX: Progressive Enhancement with AJAX.

I've just recently found the slides to the presentation and must say that I like the concept a lot.

A whole lot.

In a nutshell, what Mr. Keith advocates is that we develop webapplications with AJAX in mind, but in a traditional postback form. Minus any form of JavaScripting (such as .NET's Link buttons with are traditional A tags but with a JavaScript function as the HREF).

Then once the application is built, go back and build JavaScript which hijacks the application's links and button submissions and passing the data through the XMLHttpRequest object.

The whole purpose of the thing is to ensure that the application degrades well in downlevel browsers and/or those browsers with JavaScript turned off.

I suggest you go look at them slideshow, it's a great working platform for rolling out AJAX applications.