I asked a friend of mine to program up a sprite sheeter like this and I think this might be useful for some of you guys on here.
Basically, you load up a folder of sprites (for instance, exports from a program like flash, photoshop, after effects or a 3D render), specify the start frame, end frame, columns of each animation in the folder, then press the button and presto, each animation is made into it's own sprite sheet. You can also save the animation list in case you make changes to your animations or have other characters with the same animation. It's way quicker than doing one sprite sheet at a time, especially if you have 18+ animations for 10+ characters (in that case, do it 10 times or 180 times, your call).
Check it out, if you've got any suggestions for it, let me know and I'll forward it to the respective party.