<html>
<head>
<script language="JavaScript">
function point_it(event){
pos_x = event.offsetX?(event.offsetX):event.pageX - document.getElementById("pointer_div").offsetLeft;
pos_y = event.offsetY?(event.offsetY):event.pageY - document.getElementById("pointer_div").offsetTop;
document.pointform.form_x.value = pos_x;
document.pointform.form_y.value = pos_y;
}
</script>
</head>
<body>
<div id="pointer_div" onclick="point_it(event)" style="background:url('your_image.jpg') #ddd; width:500px; height:400px;"></div>
<form name="pointform" method="post">
X = <input type="text" name="form_x" size="4" /><br />
Y = <input type="text" name="form_y" size="4" />
</form>
</body>
</html>