I've been thinking about something like this being implemented on the web in the future if it hasn't been already, but it's kind of a strech.

Coulding AJAX be combined with MySQL and a programming language (besides Javascript) like PHP to create a real-time web forum? This sounds like a glorified chat client, but there are a lot of features that forums have that a simple chat room wouldn't.

VBulletin already implements some AJAX, and I think it does it quite well--it's not intrusive and not annoying.

The reason why few forums will implement AJAX is that it generally doesn't degrade gracefully, and people with screen readers or those who disable JavaScript will not be able to view the page.

vBulletin's implementation is minimal--from what I gather, it's simply used to speed up administrative processes. WHT uses it for quick replies and post editing.

Coulding AJAX be combined with MySQL and a programming language (besides Javascript) like PHP to create a real-time web forum?

Ajax simply allows transparent server-client connections. Its a combination of javascript, its supported HTTP Request object, and generally XML for parsing the results. The page that you send the request to can be written in any language, using any backend system.

However, a forum that runs entirely on ajax would be a bad idea.

Anything that relies on AJAX to function should include a noscript alternative for people with Javascript disabled.

If you do create an AJAX based forum, you should include a link at the top for a non-javascript version

It looks like this: http://ajax.k4bb.org/

I too have been considering the idea of a forum making greater use of AJAX concepts.

Many forums have reached the point that replies and topics are being made in near real-time, similair to a chatroom. In such cases, a system that would allow more rapid/instantaneous feedback would be advantageous. Getting rid of a users need to hit reload or to load entirely new pages to view another section of the site would be a good thing if done properly...

Of course, the key is to make the functionality optional - let it degrade into a standard forum environment for people that don't want it/can't use it.