here is an example addthis code mixed with the javascript bookmarking script
all you have to do is signup with addthis to get you id and insert it in the following code where it says YOUR ADDTHIS ID HERE
Code:
<script>
function setBookmark(url,str){
if(str=='')str=url;
if (document.all)window.external.AddFavorite(url,str);
else alert('Press CTRL and D to add a bookmark to:\n"'+url+'".');
}
</script>
<!-- AddThis Bookmark Button BEGIN -->
<a href="http://www.addthis.com/bookmark.php" onclick="addthis_url = location.href; addthis_title = document.title; return addthis_click(this);setBookmark(parent.location.href , document.title );" target="_blank"><img src="http://s9.addthis.com/button2-bm.png" width="160" height="24" border="0" alt="AddThis Social Bookmark Button" /></a> <script type="text/javascript">var addthis_pub = 'YOUR ADDTHIS ID HERE';</script><script type="text/javascript" src="http://s9.addthis.com/js/widget.php?v=10"></script>
<!-- AddThis Bookmark Button END -->