<p>The title sort of explains itself. I am making some 'genrative' artwork in flash. Now I want to save the frame without making a screenshot so-on and sofort. And perhaps one day i would like to save a batch of frames. </p>

<p>Is there an AS3 class/library out there that could help me out ?</p>

Do you want to save the file to a hard-drive or to a website?
If to a hard-drive, you might have a hard time unless you're open to using Air. Because of the security sandbox of Flash, you can't write arbitrary files to the user's hard disk.
If you absolutely must save it to a user's hard-drive using Flash and not Air, you'll probably have to send the bitmap data to a server-side PHP (or similar) script which will then allow the user to download and save the image in one location or another.