<div id="pointer_div" onclick="point_it(event)"
  style = "background-image: url('bild.png'); width: 123; height: 123;">
  <img src="pin.png" alt="pointer" id="cross"
    style="position: relative; visibility: hidden; z-index: 2;">
</div>

<script language="JavaScript">
/* get click position */
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;
    set_pointer(pos_x, pos_y);
}

/* position pin image */
function set_pointer(x,y) {
    var cross = document.getElementById("cross");
    cross.style.left = (x - 1);
    cross.style.top = (y - 15);
    cross.style.visibility = "visible";
}
</script>