I'm here to share my secrets with you, yes, you *pointing my finger*
Do you wanna do stripes perfectly organized like this?
<img src="http://dl.dropbox.com/u/47035927/Templates.png" border="0">
(Please note that templates are Original Arts Copyright, you're allowed to use in non-commercial games if you give credits)
Simple. Make your animations in GIFs, export all the frames using GIFFrame.exe and zip it. If you want the frames organized in order, make sure to select the files in order, or add one by one inside the zip.
The order used to zip will the the order placed in the strip mosaic.
I limited the resulting PNG width to 2048 pixel and the height is unlimited.
So, after finishing your zip, upload here: Famous GRID.SWF and it'll make his magic! =P
I'm not a programmer, but I learned Flash and AS2 only to make this tool for people who like make games. I was working in a version where you can select the images directly from the Selecting Box, and them it upload the images, create miniatures and give you the liberty to rotate, re-size, select the transparent color for background, align, change the order. But, very limited by my short time for this hobby I give up with the tool half finished.
Anyway, feel free to help making this tool a reality =P