I would like to build a drop down similar to the ones they are using here, exept on click not rollover:
http://www.apple.com/startpage

Any ideas where I could look to get started on finding some information?

Thanks a lot!

I’m assuming you’re referring to the accordion sliders on the left hand side? Those wouldn’t necessarily be AJAX—though they ARE javascript. I’d check out jQuery for that, it’s not too difficult really. Check out this tutorial of sorts: http://docs.jquery.com/UI/Accordion