Well, it depends. Is the method of doing it via AJAX faster or more effecient? For example, as you said when we rated ZT's code for the Coding Contest, that it would be faster to modify normally or use the Quick Reply normally.

However, if you have the file submit data to a file specifically made to handle AJAX requests (Such as the chat room you mentioned, sort of like vB's), then I think it is more effective.

I'm still not a real big person with AJAX, as in knowing what it is and what's it truly about. So I probably sound like a dumbass right now.

It depends what your using it for. if it is a web application such as Gmail then I think it is a good idea. In that case it makes the web app. much faster and more efficient. But when used for everyday things it's just kind of useless. In my opinion I don't think it's overused. The only times I see it is when it is put to good use.

In a sence its overused, i suppose people are just trying to show they have a knowledge of the code, still i'd use a much more simplier method to solving a problem then just going all out on loading time etc. But yeah it does depend on the situation, though i do like how it works on vBulletin when posting, its kinda spiffy to see working.

I normally use iframes but recently have been getting in to use Ajax's XMLHTTPRequest object. People on the Invisionfree forums use it all the time so i thought i may as well learn. It's used alot yes but it's very helpful and faster than using iframes.