Add Extra Code to Any Menu

gistfile1.php

<?php
/**
 * Add Extra Code to Any Menu
 * @author Bill Erickson
 * @link http://www.billerickson.net/customizing-wordpress-menus/
 *
 * @param string $menu
 * @param object $args
 * @return string modified menu
 */
function be_menu_extras($menu, $args) {
	if( 'secondary' !== $args->theme_location )
		return $menu;
	return $menu . '<li class="right">Your extras go here</li>';
}
add_filter('wp_nav_menu_items','be_menu_extras', 10, 2);