If you've been looking for a way to make an effective image gallery for your site, but don't want to "cheat" and just resize the images (that doesn't change the download time anyway), then Codewalkers might just have your answer.

In their latest tutorial, Thumbnails in PHP, they show you how to take an image, and, using the GD libraries (bundled with PHP these days), create a script that will grab the image name from the img src in your HTML, and automatically create the thumbnail for it. This is an "on the fly" translation, and not a "before the fact" resizing, so it will be a little slower, but still effective. The only image your viewers will see will be the end result - the thumbnail.

Each chunk of code is well documented and shows you exactly what things are doing behind the scenes, in case you want to change something.