Some time ago i wrote a script for a client, who had the urgent need of a dropdown navigation for his site. So here is some code...

knallgrau/code/unordered-list-as-dropdown-menu

Many javascripts are dealing with this issue, but a lot tend to rely on complex html, or even js code to create a menu structure, which doesn't conform to the w3c Accessibility Initiative nor it is readable for developers and site maintainers.

In this example i used a simple unordered list for creating the menu structure.