Marcus Downing

When writing or modifying a theme, the function wp_nav_menu() displays the contents of menus configured in your settings. If you have a lot of little menus the list can get hard to manage, so this plugin lets you group several menus under a single menu.
To use it, simply add a <code>submenu</code> parameter to the arguments of wp_nav_menu, like so:
<pre><code>wp_nav_menu(array(
 'menu' => 'header',
 'submenu' => 'About Us'
));
</code></pre>

Subtitle Filter

Adds tha ability to show only a submenu with wp_nav_menu().

tormorten

A simple plugin to move the WordPress nav-menu item out of Appearance.
This way clients get access to the menus, but can still limit access to the other stuff under “Appearance”.

Move Nav-Menu

Moves the WordPress nav-menu item in admin to a new top level page. Out of "Appearance".

Subtitle Filter vs Move Nav-Menu