<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
<script type="text/javascript">
function showHidePanel()
{
$("#myPanel").animate(
{
left: parseInt($("#myPanel").css('left'), 10) == 0 ?
$("#myPanel").outerWidth() : 0
});
}
</script>
<div>
<div onclick="showHidePanel();">
XXX
</div>
</div>
<div id="containerDiv" style="position: relative;width:800px;border: 1px solid #cecece; overflow: hidden;">
<div id="myPanel" style="position: absolute;margin-left:700px;">Боковая панель</div>
<div id="Data">сайт</div>
</div>
</body>
</html>