Adobe Flash CS3 - Newest version of Flash and the first to be published by Adobe. This is the ONLY program that Armor Games supports for games on the website, unless you have another way to create an .swf file. Cost: $699 (30-Day Free Trial Available roduct=flash">HERE)
Game Maker 7 - An extremely popular program that's used by many indy developers to create games. It's extremely easy to use, and is great for those of you starting out. Cost: Free!
This topic is a work in progress and will be edited to include more programs at a later date. If you want to see a program added, or need help with game development, please leave me a comment of my userpage. Thank you.
A good alternative to CS4 is Flash Develop. Flash Develop Main Page It's an open source (free) actionscript source code editor. To compile, you'll need to download Adobe Flex SDK (also free), and this website also has links to a walkthrough on how to do that. Hope this helps any aspiring flash developers who (like me) are way to poor to shell out for CS4.