Ajax is really cool Web technology. In case you aren't aware of what it can do, it's an enabler that can make Web apps function like a desktop app -- e.g. Parts of the screen can be redrawn with new content without the need to reload an entire Web page.
Read this article over at IT Observer to get a better picture of what to look for. And if you want to see some super slick Ajax applications in action then head over to ajaxLaunch.com where you'll find that Michael Robertson (founder and former CEO of Lindows ... errr ... Linspire) is working to produce Ajax-based applications beginning with ajaxWrite, which is compatible with MS Word documents, and ajaxSketch, which lets you create charts and diagrams. Also check out eyespot.com , which is an Ajax-based video editor!
All these tools are excellent examples of where the Web is headed in terms of functionality. It's exciting, but at the same time I find more than a bit disturbing. The reason is that we could be headed towards a software market that will push very hard for acceptance of complete on-demand application access, which if handled selfishly could mean that you lose control over your own desktop. Think about the ramifications of this scenario for a few minutes...