I wrote this one page Image Gallery script for use in my Client Previews sections - to allow clients to view online, all the images available to them for print and album ordering selection. Like all of my other scripts I write them so that everything is as automated as possible and in the case of the OPG, requires no more work than uploading the "index.php" to a folder of images and thumbnails. This script contains the complicated math required to go back and forth between an index page with many small contact sized images, and the corresponding full size image - plus use the Previous/Next links to act as a slide show. Configuration of names, urls and colors and cell sizes, is at the top of the page so you can customize it to look the way you want.