zackdesign

Note: This plugin requires PHP 5
Warning: This plugin requires knowledge of CSS to use adequately in widgets
Features at a glance:
<ul>
<li>Widgetised to make it really easy to add multiple dropdowns anywhere on the page you have sidebars</li>
<li>Ability to create the menu wherever you want with PHP Classes</li>
<li>Leverages the new WordPress 2.8 widget settings to allow quick and easy multiple widget instances</li>
</ul>
Theming options:
<ul>
<li>Multi-level dropdown (CSS included)</li>
<li>Multi-level left/right flyouts (CSS included)</li>
<li>Support for Superfish Javascript (CSS included)</li>
<li>Works with other CSS (within reason)</li>
</ul>
If you want me to modify the CSS for you simply <a href="http://www.zackdesign.biz" title="Zack Design" rel="nofollow ugc">contact me</a> and I will do it easily and quickly for you for a moderate sum.
It uses <a href="http://www.cssplay.co.uk/menus/final_drop.html" title="Stu Nicholl" rel="nofollow ugc">Stu Nicholl’s final drop-down code</a> which is a complete CSS solution – no Javascript required!!
You can look on <a href="http://www.cssplay.co.uk/menus/" title="Stu Nicholl's Menus" rel="nofollow ugc">Stu’s site for other drop-down code</a> as I got the flyout left and right code from there. Don’t forget to donate if you’re using his styles.
Most of his CSS should work just fine with the menu. I’ve made it so that the plugin automatically finds menu.css in the plugin’s folder and loads it in your WordPress site so you can instantly see how it will look. If you want to create your own CSS simply create menu.css in your theme’s root directory and the plugin will load that automatically for you.
Please note that if you’re upgrading you will need to change your theme files to suit the new approach. See Installation for further information.

WordPress CSS Drop-down Menu

Use Wordpress' nav menu system to create left/right widget flyouts, with support for Superfish

Tobias Nyholm

Webfish Dropdown Menu gives the site admin the alternative to add a dropdown menu. 
This plugin does not require any programming or adding lines in the source code. 
 Simply just activate the plugin, rename a menu, then customize it from the admin panel.
Webfish Dropdown Menu uses CSS to display the menu. There is no javascript included.
This plugin does not support the following at the current version:
<ul>
<li>vertical menus </li>
<li>background images for the submenu </li>
<li>multiple dropdown menus</li>
</ul>
For more information see installation page or the 
<a href="http://www.webfish.se/wp/plugins/webfish-dropdown-menu" title="Webfish - WordPress plugin" rel="nofollow ugc">Webfish</a> homepage.

Webfish Dropdown Menu

If you want a simple dropdown menu on your site and have no knowledge of coding, this is the plugin for you.

WordPress CSS Drop-down Menu vs Webfish Dropdown Menu