I made this script to create thumbnails for images in a directory that already has existing thumbnails in it. It will make a list of all images bigger than 100px X 100 px. Smaller images are ignored. For the bigger images, thumbnails with links to the images are created. The results are paginated - 25 thumbs per page. Title, header and table of contents are created automatically.
The script can also select images at random ($self?rand=full) for a Random Slide Show ($self?img=slideshow) or random thumbs ($self?rand=thumb)
To use, transload http://eclecticdjs.com/mike/temp/ball/thumbs.txt and rename it to .php. If you want to change the number of thumbs per page, change the variable $per_page at the top.