I am working on a Magento site and my customer has requested a menu system to behave like http://www.rei.com and http://www.att.com. They want the menu to have main links across the top like both examples. Then a user clicks or mouses over (either way would work) a single line of sub categories is show across the bottom of the main links. Then when the user mouses over those sub categories the mega menu shows with sub-categories and sub-sub categories.

Does anyone know of a good plugin or way to program this?