It wouldn't be hard to build your own. You could have a page that shows an animated gif and then loads the page using AJAX. You can get some great loading gifs just by searching for something like "AJAX loading image". This may or may not seem easy to you, but it doesn't sound too hard to me if you were using jQuery and PHP.
Example
Say you have two files: test1.htm and test2.htm. You want to show the contents of test2 (which take a bit to load) on test1 (which should have the parts of the page that load quickly). Here's the two files I made (this uses jQuery):
test1.htm
<head>
<script language="javascript" type="text/javascript" src="jquery-1.3.2.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$.get('test2.htm', function(data) {
$('#Content').html(data);
});
});
</script>
</head>
<body>
<div id="Content" >
<img src="ajax-loader-image.gif" />
</div>
</body>
</html>
test2.htm
<h2>Dynamically Loaded Content</h2>
<p>Hello World!</p>
So this should work for what you're planning to do. The important thing is that you try to divide up your page into parts that load quickly and parts that load slowly.