A couple of days ago Saul Rosenbaum asked for a little help with a PHP utility he was writing. I took a crack at it, and we ended up with a nice little class that generates CSS sprites from pairs of images. Saul wrote a great little README for it, but the general gist is that it takes a00.gif and a00_over.gif and creates a new a00.gif that has both images vertically stacked within it (it can do this with large batches of images).
We submitted the files to IndyHall Labs if anyone is interested in using them. If I have time I’ll be adding some new functionality (Saul added a wishlist in the README file, and I’d definitely love to tackle some of those issues).
You can download the files from GitHub: https://github.com/IndyHallLabs/css-sprite-generator/