A function that adds a separator to the WordPress Dashboard menu. Call add_menu_separator($position) with a number parameter.

wp-menu-separator.php

<?php

/**
 * add_menu_separator function.
 *
 * A function that lets you add a menu separator on a given menu position.
 * 
 * @access public
 * @param mixed $position
 * @return void
 * @author Teo Maragakis
 */
function add_menu_separator($position) {
  global $menu;
  $separator = array(
    0  =>  '',
    1  =>  'read',
    2  =>  'separator' . $position,
    3  =>  '',
    4  =>  'wp-menu-separator'
  );   
  $menu[$position] = $separator;
  ksort($menu);
} ?>

// Example
add_menu_separator('29');