<p><div id=\"tags_d\">no tags</div></p>  //build tag list here
<p>
<span id=\"tags\">+add new tag</span> &nbsp;

<script>
new Ajax.InPlaceEditor($('tags'), 'tags.php', {
       ajaxOptions: onComplete: function (transport, element) {               document.getElementById(\"tags_d\").innerHTML = transport.responseText;
              document.getElementById(\"tags\").innerHTML=(\"+add new tag\");

              }
             })
</script>