there is none but dont fret there are 2 good game makers which are free sadly they only let you upload the games on their respective sites although gamemaker lets you download the files so you could post them on the net on other sites to be downloaded and played here they are
Yeah, FlashDevelop is the only entirely legal and free one I know of, but its harder to learn as it deals entirely in actionscript and there isn't a user friendly stage and whatnot like in adobe CS3 or CS4 :P
But if you're willing to learn then you should try FlashDevelop. Google it if you want to know more.
If you try using Flash Develop, at least for the first few times, I'd recommend using Flixel or a similar engine. That should help adjust you to the actionscript used in FlashDevelop.
Necro thread is necro. Other than that: flixel is a framework, not a standalone program you can use to create games. For programming flash, your choices are roughly Flash CS5, flashdevelop or FDT, of which only flashdevelop is free