This is a simple Accordion collapsing menu done in JQuery. Links with subitems under them will expand the submenu when clicked. Items that don't have subitems are normal links.. The menu initialises with the first submenu expanded.

Javascript

     function initMenu() {
    $('#menu ul').hide();
    $('#menu ul:first').show();
    $('#menu li a').click(
    function() {
    var checkElement = $(this).next();
    if((checkElement.is('ul')) && (checkElement.is(':visible'))) {
    return false;
    }
   if((checkElement.is('ul')) && (!checkElement.is(':visible'))) {
   $('#menu ul:visible').slideUp('normal');
   checkElement.slideDown('normal');
   return false;
   }
   }
   );
   }
   $(document).ready(function() {initMenu();});