This jQuery Menu plugin can be used to create a simple dropdown menu for a single list of options, a flyout menu for a smaller hierarchical list of options where child menus are displayed next to the parent menu on mouseover, and two variations on the iPod style menu: one with a back button and another with a linked breadcrumb to let users easily traverse back up the hierarchy.
jQuery Menu plugin requires jQuery 1.3 and provides you the ability to customize appearance by passing in classes as options. It also allows you to plug in jQuery UI CSS Framework classes so that the menus can be styled on the fly using ThemeRoller. Although calling the menu plugin departs slightly from how jQuery normally works; incorporating it into your webpage is still pretty straight forward.
Developed by Filament Group; jQuery Menu Plugin is available for download under MIT license. You can find further information, demo & download on Filament Group Website.