I bought an addon AllWebmenupro that does this for me.. http://www.likno.com/index.html but mine doesn't seem to have quite what you are looking for. I may be wrong, but it seems that drop down menus must either be using javascript or flash, or something more then you normal html.. If you do not have this knowledge best to look around for something, you may even find a free one..
You do a "pull down" in HTML. But anything more advanced will require JavaScript.
I would recommend a DHTML menu using divs for better search engine spidering. try dynamicdrive.com