$(function () {
    // find submenus
    var $submenus = $('#navigation ul ul');

    // and hide them first
    $submenus.hide();

    // now bind the hover event of the parent
    $submenus.parent().hover(
      function over() {
        var $this = $(this);
        $('ul', this).css('top', $('a', this).innerHeight()).slideDown('fast');
      },
      function out() {
        $('ul', this).slideUp('fast');
      }
    );
  });