My most recent article about customising WordPress has appeared on the Peachpit site. It’s about editing the footer of your blog — Make a Lasting Impression:
The footer may be the last thing visitors see on your blog. It leaves a lasting impression, so you should use it well. In most themes, a separate file called footer.php contains this part of the site. In this article, you’ll learn how easy it is to edit the footer to display exactly the information you’d like your blog’s visitors to see.