I do this sort of thing at work all the time. We use these kinds of things in games quite a lot. They are called Filmstrips, Flipbooks, or Atlas Textures, depending on who you ask. I have some custom photoshop scripts that take a specified folder of images, then they create a big long strip using those images. From there, you run another script that chops up your long image sequence into a square page of images.
Unfortunately the script is in-house only, NDA's and such.. So I cant provide a whole lot of insight on it. There might be something laying around the web..
Now that I think about it, nVidia has a util called AtlasCreationTools, made specifically for this, and it's a public tool you can find on their site somewhere.
edit: here you go!
http://developer.nvidia.com/object/text ... tools.html