I'm not aware of any, no. I'd just write my own.
<!-- place this in your <head> -->
<script type="text/javascript">
function hideLoading() {
document.getElementById("loading").style.display = "none";
}
if ( window.addEventListener ) { // Mozilla, Netscape, Firefox
window.addEventListener( "load", hideLoading, false );
} else { // IE
window.attachEvent( "onload", hideLoading );
}
</script>
<!-- place this wherever you want the "Loading" graphic to appear -->
<img id="loading" src="whatever.png" />