I have added a small 'Share On Facebook' widget to the bottom of my posts. You can see an example of it here :
http://theimpossibleprincess.wordpress.com/2008/09/30/kylie-films-comedy-cameo/
The code for the widget on this page is :
<p class="sharefb"><a href="http://www.facebook.com/share.php?u=http://theimpossibleprincess.wordpress.com/2008/09/30/kylie-films-comedy-cameo/" target="_blank">Share On Facebook</a></p>
Each time I use the widget I have to manually change the URL of the post in the above code. Is there a way to dynamically (if that's the right word) generate the post URL in the code?