//menu
$(document).ready(function(){
  $('li.mainlevel').mousemove(function(){
      $(this).find('ul').slidedown("1000").stop(true, true)
;//you can give it a speed
  });
  $('li.mainlevel').mouseleave(function(){
      $(this).find('ul').slideup("fast").stop(true, true)
;
  });
});