A few weeks back I posted about Nina Paley's masterpiece Sita Sings the Blues, which is free to watch on her site. Being the good creative commons kind of sport that Paley is, she just recently made available the original Flash files for the movie at Internet Archive. So if you're a budding animation artist and want to know how she accomplished a certain effect, here is your chance to examine in detail the inner workings of the Flash scripts.
From her blog:

All the Flash authoring (.fla) files I used to make Sita Sings the Blues have just been posted on archive.org, under a Creative Commons Share Alike license. Want to know how I got a certain animated effect in Sita Sings the Blues? Open up the .fla files and find out. Want to remix from the source? Now you can. Want to make a Sita Sings the Blues video game using all the assets? Go for it. (But I strongly suggest you negotiate my endorsement if you want to actually market the end product...Yes, I know bad bad people can also use the .fla files for dastardly deeds (the dreaded hypothetical “Nazi Porn Version” that always comes up at Q&A’s). Bad bad people can use our shared Language and Technology for evil too, but I’m not going to constipate culture out of fear of imaginary worst-case scenarios. I’m confident much more good will come from this than bad, and that’s motivation enough for me. It’s Free Culture, baby. If programmers can tinker with the Free Software’s source code, artists can tinker with Sita Sings the Blues‘ source files.