Tooltip Question

Just wondering if someone has some advice on dynamic tooltip. By that I mean, I want the text inside the tooltip to be automagically generated from a text file.
I have not included any code example because, there are tons of tooltip examples but I can't find one that will use a text file to populate the tooltip.

Thanks for any help
-Chris

In case anyone finds this useful
Here is the code that I needed.......

Place text files report_file.txt and report_file2.txt are in the same dir as html -- or path them out in the code....

<html>
   <head>
      <title>System Reporting</title>
      <script type="text/javascript">
         function showBox(file_name, id, obj) {
            var helpNode = document.createElement('div'+id);
            helpNode.id = 'popBox'+id;
            helpNode.setAttribute('class','popBox');

						var el = document.createElement("iframe");
						el.setAttribute('id', 'ifrm');
						helpNode.appendChild(el);
						el.setAttribute('src', file_name);

            obj.appendChild(helpNode);
         }

function hideBox(id) {
   var node = document.getElementById('popBox'+id);
   node.parentNode.removeChild(node);
}
</script>
<style type="text/css">
   .popBox {
      position: absolute;
      z-index: 2;
      background: #cccccc;
      width: 600px;
      padding: 0.3em;
      border: 1px solid gray;
   }
   span {
      color: red;
      font-weight: bold;
   }

   iframe {
      border: none;
      width: 600px;
      height: 200px;
   }

</style>
</head>
<body>
      <div onmouseover="showBox('report_file.txt', 'file1', this)"
				onmouseout="hideBox('file1')"
style="cursor:pointer"><span>HOST 1</span><br/></div>


    <div onmouseover="showBox('report_file2.txt', 'file2', this)"
				onmouseout="hideBox('file2')"
style="cursor:pointer"><span>HOST 2</span><br/></div>

</body>
</html>