phpThumb
[locked]
To sum it up, phpThumb is a PHP project that lets PHP applications generate thumbnail images on the fly. It's works with PHP's GD library, so you need to have it setup correctly in order to use it. When the GD library is up and running, installation is quite simple. You simply need to unpackage the set of files somewhere on your server.
phpThumb supports GIF, PNG, and JPEG image formats. Thumbnail images can be sized with a quick parameter or two. It can even show a portion of an image for a thumbnail (rather than having a thumbnail of the entire source image). Best of all, images are cached to help loading images.
Strange Things I've Encountered
No serious problems, but I am still having trouble getting GIF files to work correctly. Apparently, they are supported on all versions of GD with a specially written "GIFutil" class. I'll admit that I haven't looked into this yet. I'll be sure to update this wiki entry when I find out more.
Resources
Enabling PHP's GD Graphics Library (w)
phpThumb - The Thumbnail Creator (external)