Create Navigation Menu Easily with jQuery Menu
jQuery Menu is a solid menu system that helps creating dropdown, iPod drilldown and flyout styled navigations easily. The menu system uses a hierarchical unordered list for creating the menus & sub-menus. It is ready with ThemeRoller which makes it very easy to customize the look and has ARIA (Accessible Rich Internet Applications Suite) support.

With various configuration options & ease of use, jQuery Menu is definitely a very helpful solution for creating menus.
Requirements: jQuery, jQuery UI
Compatibility: All Major Browsers