[ilike]

Apart from the links 'geeymb' posted, FlashDevelop is a popular free tool to create flash content [flashdevelop.org]

Scribd uses 'pdf2swf' from swftools.org to convert pdfs(Not sure if they still use it. ref: http://www.swftools.org/references.html )

Scaleform depends heavily on Flash[scaleform.com]. Ming library is a nice option to create dynamic swf files on server side[libming.org].

A nice little online editor and compiler can be found here: http://www.victordramba.com/?p=31

Although there are so many nice, robust open source tools built around Flash, i haven't heard of Adobe actively promoting any of them.