WordPress: Helpful nav menu classes.

gistfile1.php

<?php
add_filter( 'wp_nav_menu_objects', 'blazersix_nav_menu_classes', 10, 2 );

/**
 * Add helpful nav menu item classes.
 *
 * Adds class hooks to various nav menu items since child pseudo selectors
 * aren't supported in all browsers.
 */
function blazersix_nav_menu_classes( $items, $args ) {
	$classes = array();
	
	foreach ( $items as $key => $item ) {
		if ( empty( $item->menu_item_parent ) ) {
			$last_top = $key;
		} else {
			if ( ! isset( $classes['first-submenu-items'][ $item->menu_item_parent ] ) ) {
				$classes['first-submenu-items'][ $item->menu_item_parent ] = $key;
				$items[ $key ]->classes[] = 'first-sub-menu-item';
			}
			$classes['last-submenu-items'][ $item->menu_item_parent ] = $key;
		}
	}
	
	$items[1]->classes[] = 'first-menu-item';
	$items[ $last_top ]->classes[] = 'last-menu-item';
	
	if ( isset( $classes['last-submenu-items'] ) ) {
		foreach ( $classes['last-submenu-items'] as $item_id ) {
			$items[ $item_id ]->classes[] = 'last-sub-menu-item';
		}
	}
	
	return $items;
}