The iPod Drilldown and Flyout Styles Menu System 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, one with a back button and another with a linked breadcrumb to let users easily traverse back up the hierarchy.

It provides easy navigation of complex nested structures with any number of levels. They also built in the ability to customize a menu’s appearance, including active and hover states, by passing in classes as options.

Requirements: jQuery Framework
Demo: http://www.filamentgroup.com/lab/jquery_ipod_style_and_flyout_menus/
License: MIT, GPL License