You might check out these posts as well:
Horizontal and vertical drop down menus
1) Drop Down Tabs (5 styles)– Drop Down Tabs is a horizontal CSS tabs menu that supports a second level drop down menu for each of its tabs.
4) FastFind Menu- A jQuery nested menus, based on dynamic “AJAX” responses. The menu can also be dragged/dropped.
5) jQuery SuckerFish– Replicate Suckerfish Menus.
7) List Based Menu with Images– This is a menu based on an unordered list (<UL><LI>). It makes the menu easy to use and friendly to search engines.
8 ) Slide down menu– A slide menu based on an unordered list (
9) Dropdownmenu made with scriptaculous/prototype– A multi level drop down menu.
10) Suckerfish-style menu plugin for jQuery– This demonstrates a two-tiered horizontal menu that displays the path to the current page when the menu is in its idle state.
12) onMenuOpen onMenuCollapse Events- This is a one-time effect that shows off the menu opening up and firing an event, and then finishing with another event.
13) Mootools menu with accordion and effects- This simple menu has a neat effect by hovering over the links, and opens a submenu with an accordion.
14) Mootools Unlimited Drop Menu
15) Creating an Outlook Navigation Bar– Using the ListView and Accordion Controls
17) Drop down menu with Prototype– A unique drop down navigation that recursively applies a function to an li that toggles the visibility of a nested ul element.
19) Drop down menu with jquery– A drop down animated menu example made with jquery
20) jdMenu Hierarchical Menu– The jdMenu plugin for jQuery provides a clean, simple and elegant solution for creating hierarchical drop down menus for websites to web applications.
21) jQuery plugin: Treeview– Lightweight and flexible transformation of an unordered list into an expandable and collapsable tree, great for unobtrusive navigation enhancements.
22) Drop Down menu
24) Accordion Menu script– This example illustrates how you would add a collapsible sub level.
25) Complex Dynamic Lists– Using an unordered list, to display a hierarchical structure of a complexity that would be very hard to achieve with dynamic select boxes.
Drop Down Menu Tutorials
CSS Express Drop-Down Menus– CSS Express menus should only be used in a horizontal orientation with a single drop-down level.
Drop Down Menu Generator
Izzymenu– With an impressive Ajax interface, you can build your own CSS drop down DHTML sub-menu in minutes without writing a single line of code.