For one of our current projects we are building a website where the design dictates that most of the content is presented using a dropdown menu approach. Normally, a dropdown functions best when all of the content is already loaded on the page, and just relies on javascript to animate the display and hiding of each dropdown element.  For this design, it is pretty obvious that requiring all of the overlay content to load along with the initial page is excessive for both load times, as well as complicated for the CMS organization and structure. AJAX to the rescue!