Banhawi

The new wordpress 3.0 custom menus feature is one of the best newly added features to wordpress that gives you more control on your menus every where on your web site .
Wordpress new custom menus works in simple two steps .

First : Register the menu

register your menus in your theme’s functions.php file

register_nav_menus( array( $location => $description ) ); 

Real Example

if ( function_exists( 'register_nav_menu' ) ) {
register_nav_menu( 'topnav', 'Top Navigation' );
}

you can register as many custom menus as you want .

Second : Place the menu

Now it’s time to place your menus where you want it to be showed on your theme

<?php wp_nav_menu(); ?>

That’s it , now just play with your wordpress menu designer and have fun

Functions Used : register_nav_menus &  wp_nav_menu