The Motion-Twin ActionScript Compiler will allow you to create Flash apps for free… using full ActionScript 2 syntax, and even has some improvements in the compiler to variable checking and such.
You should know that I am not a Flash developer, so I don’t really have any idea how good this thing is, but it claims to faster than the Macromedia compiler, and to generate the same SWF bytecode … without relying on costly tools [;-)].
If you’re into Flash, you should check out the OSFlash Wiki they have a ton of open source tools over there, including an amazing number of free flash and action script editors, compilers, unit testing tools etc.
P.S.: I’m posting this from the diigo “blog this” interface … cool, but limited.