I recently had a need for some client side script that could sort a select input's options alphabetically. At first I wasn't sure if there would be an easy way to do that with jQuery, but...
So you want to get down and dirty with some Ajax do ya? If you're looking for a way to pass data to and from a PHP script and handle the results, you've come to the right place my friend!
Recently I was working on a project where I was trying to improve the usability of a fairly heavy form. My strategy was to progressively show items as the user clicked on relevant inputs.