What is AddThis?
AddThis spreads your content across the Web by making it easier for your visitors to bookmark and share it with other people, again…and again…and again. Our simple yet powerful widget is very easy to install and provides valuable statistics about the bookmarking and sharing activity of your users. AddThis is the perfect tool to help your visitors create a buzz for your site and increase its popularity and ranking.

Not sure how to use this.

<!-- AddThis Bookmark Button BEGIN -->
<a href="http://www.addthis.com/bookmark.php" onclick="window.open('http://www.addthis.com/bookmark.php?wt=nw&pub=jtfmulder&url='+encodeURIComponent(location.href)+'&title='+encodeURIComponent(document.title), 'addthis', 'scrollbars=yes,menubar=no,width=620,height=520,resizable=yes,toolbar=no,location=no,status=no,screenX=200,screenY=100,left=200,top=100'); return false;" title="Bookmark using any bookmark manager!" target="_blank"><img src="http://s9.addthis.com/button1-share.gif" width="125" height="16" border="0" alt="AddThis Social Bookmark Button" /></a>
<!-- AddThis Bookmark Button END -->