Gone are the days of clicking, submitting, and waiting for the next page to load, or manually compiling your own content from all your various online identities to post into your site.
A web page using AJAX techniques (if applied properly) will give the user a smoother and leaner experience. Click on a drop-down option and the checkbox menus underneath are updated immediately with the relevant choices—no submitting, no waiting. Complicated forms which, in the past, took two or three screens to process can be reduced into one convenient screen by implementing the form with AJAX.
As wonderful as this all sounds, I must again offer a quick disclaimer. I understand, as with drop-down menus and Flash, you may want or your clients are demanding that AJAX be in their sites. Just keep in mind that AJAX techniques are best used in situations where they truly benefit the user's experience of the page—for example, being able to add relevant content...