Ted jsem po tom koukal na netu kvuli Losovi a našel jsme tohle:

<a href="" onMouseOut="Hide()" onMouseOver="Show()"
  onMouseMove="Show()"><img src="www.dottedi.biz/images/css_bg.gif"
  alt="CSS image" title="This should display in Firefox" border="0"></a>

  <script language="javascript" type="text/javascript">
   
    function Show()
    {
        /* get the mouse left position */
        x = event.clientX + document.body.scrollLeft;
        /* get the mouse top position  */
        y = event.clientY + document.body.scrollTop + 35;
        /* display the pop-up */
        Popup.style.display="block";
        /* set the pop-up's left */
        Popup.style.left = x;
        /* set the pop-up's top */
        Popup.style.top = y;
    }
    function Hide()
    {
        /* hide the pop-up */
        Popup.style.display="none";
    }
    </script>

<div id="Popup" class="transparent">
    <div style="background-color: #003366"><b>Title goes here - as you 
wish...</b></div>