What is GD? GD is a standard graphics library that has binding into lots of different languages. A modified version of it is bundled as standard with the binary version of PHP, and it can easily be compiled in to the source release with a flag.
What is phpgd.com? phpgd.com is a site that collects together many PHP GD scripts and articles. It's affiliated to DevNetwork.
tiny comment on the "Getting started with GD" area, page 3, it says to free the image to use imageclose() but thats not a valid PHP function, it should be imagedestroy().
Other than that, great site, I like it