the Addthis widget is like the AddFavorites extension....it passes the current page title and url to an external web site...You cannot use it to tag an item in a list on a web page.

If you are only showing it on a single page on your site... place the <script> block after the closing </div> tag....in your content page...

the error message you are receiving is for IE8 and higher... and is happening becuase the addthis inserts markup with the addChild method... this cannot occur in IE8 and higher without the parent element having being closed first. This (raising an error on addChild ) if the parent element is not closed is the standard behavior...IE7 is described as a 'Near Standards' browser.

I use a userControl to encapsulate the Addthis widget on my pages.

<td style="height:16px;width:126px;">

<% If isNotIE5 Then%>

<script type="text/javascript">addthis_pub  = 'iecustomizer';</script>

<a href="http://www.addthis.com/bookmark.php" onmouseover="return addthis_open(this, '', '[URL]', '[TITLE]')" onmouseout="addthis_close()" onclick="return addthis_sendto()"><img src="http://s9.addthis.com/button1-bm.gif" width="125" height="16" border="0" alt="" style="padding:0px 2px 0px 2px" /></a><script type="text/javascript" src="http://s7.addthis.com/js/152/addthis_widget.js"></script>

<%End If%>

</td>

since the Addthis widget is staticly placed you do want to display it on Quirks mode documents, since quirks mode browsers do not understand static positioning.

You can see from the above snippet how the page URL and TITLE are the passed parameters.