"

From 2012.igem.org

//menu $(document).ready(function(){

 $('li.mainlevel').mousemove(function(){
 $(this).find('ul').slideDown("1000");//you can give it a speed
 });
 $('li.mainlevel').mouseleave(function(){
 $(this).find('ul').slideUp("fast");
 });
 

});