Microsoft have some software called XNA that allows you develop on the Xbox 360. However, it is quite daunting to use for a Flash developer since C# is a HUGE step up from Actionscript.
The official XNA forums don't help much since they're focused towards normal programmers. And plus there aren't any really good simple tutorials for people to learn from. The best simple help you get is from buying books, but who wants to spend money on this?
That is why I'm looking to create some forums dedicated to going from Flash development to Xbox 360 development in XNA. The tutorials will be focused towards Flash developers, so it'll be like "this is how it's done in Flash and this is how it's done in XNA". It'll cover everything, from displaying your first graphic to making your first entire game, all made entirely user friendly for Flash developers. Plus there will be help sections and everything else a good forum needs.
And it won't just be for people with Xboxes. XNA games are developed on Windows and then ported over to the Xbox, but you can just keep them on Windows if you want :)
.
But anyway, this is just a general feeler. I'm still writing tutorials and making the forums, but if you are interested please post here. It'll encourage me to get them done sooner :)
Oh, and did I mention that all the software you need to start making XNA games is completely free? :)