The Nice Menus module support accessible drop down and fly out menus.
To use images for the top level menu, follow these instructions which explain how to use theme_menu_item_link() to swap the menu title field with the description field. The result is an accessible menu that uses Drupal permissions, image tags with alt text, and anchor tags with the title text.
It is often desirable to change the color of the Drupal menu icons, which by default, are black. The icons are located in /misc, with the folowing file names: menu-collaped.png, menu-collaped-rtl.png, menu-expanded.png, and menu-leaf.png.
To create and display a custom menu in a Drupal template, do the following:
1. Create the new menu by clicking "Add Menu".
2. Remember the machine readable name you specified.
3. Add the menu items.
4. In your template, enter the following code, replacing "machine-readable-name" with the name you entered in step 2. Note that Drupal adds "menu-" in front of the machine readable name you specified, so be sure to pre-append "menu-" in front of your machine readable name.
<?php print theme('links', menu_navigation_links('menu-machine-readable-name'), array('id' => 'menu_id', 'class' => 'menu_class')); ?>