Thanks to arts for some contributed links today. First off, WebReference.com has a section that talks about working with GD and adding images together. They use the example of adding a pin to a map. The second link is an overview of three different languages (PHP, Perl, and Java servlets) and tries to help you figure out whcih is the rigth one for you.
The last link over on Webreference.com talks about cookies and how to use them effectively. Now, it's a perl article, but it still is a good read. That's all folks!