SO fiddle

Test Fiddle mainly for SO Questions

by Nick Craver

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<ul class='nav'>
  <li><a href='#'>About</a>
    <ul class='submenu'>
      <li><a href='#'>Stuff</a></li>
    </ul>
  </li>
</ul>

CSS

.submenu { display: none; }

JavaScript

$('ul.nav li').hover(function(){
  $(this).children('.submenu').stop(true, true).slideToggle();
});