Untitled

<span id='adiv'>
Mouse over here
</span>

<div id='togglething' style='display:none;background-color:yellow;'>
Some stuff
</div>

<script type="text/javascript">
$(document).observe("dom:loaded", function() {
   $('adiv').observe('mouseover', function(){ new Effect.BlindDown('togglething', 'blind'); });
   $('adiv').observe('mouseout', function(){ new Effect.BlindUp('togglething', 'blind'); });
})
</script>