<script type="text/javascript">
function Open(id)
{
  document.getElementById(id).style.display="block";
}
 
function Close(id)
{
  document.getElementById(id).style.display="none";
}
 
function Delay(id)
{
  setTimeout("Close('"+id+"')",1000);
}
</script>
 

 
<a href="#" OnMouseOver="javascript:Open('sub1');" OnMouseOut="javascript:Delay('sub1')">Мэню1</a>
 
 
 
<div id="sub1" style="display: none;" OnMouseOut="javascript:Delay('sub1')">
<a href="/1/">1</a>
 
<a href="/2/">2</a>
 
<a href="/3/">3</a>
 
<a href="/4/">4</a>
 
</div>