jQuery Sooperfish
Copyright (c) 2012 Sooperthemes.com.
jQuery sooperfish is a mobile & touchscreen friendly drop down menu script. The script supports multi-column sub menus by automatically dividing menus into 2 or 3 columns when the number of items in a sub menu exceeds a configurable limit.
Responsive Mobile & Touch screen friendly drop down menus
With the 0.3 update touch-friendly sub menu toggling is added. For optimal touchscreen support you have to change your HTML to support non-link parent menu items. This is done by using span tags instead of a tags for parent menu items that contain sub menus. Have a look at the example-touchscreen-friendly.html for an example.
Here is a production example of a multi column responsive menu using sooperfish: http://demo.respondr.sooperthemes.com/ This Drupal theme uses the [special menu items module] (http://drupal.org/project/special_menu_items) to create the non-linked top level menu items.