Well, before you ask the question. The answer is Yes and NO! This is not an application. And technically its legal. Anyway, details about the keygen later...
Windows 7 Beta was out with a limit of 25 millions download originally intented. However, it is now limited to a 2 weeks windows.
You will need the following (as quoted from Microsoft website):
A blank DVD
A PC with a DVD burner
A test PC for the Windows 7 Beta that meets these minimum hardware recommendations (specific to the Beta and subject to change in the final version of Windows 7). Please do not use a PC you rely on for your work or daily use:
1 GHz 32-bit or 64-bit processor
1 GB of system memory
16 GB of available disk space
Support for DirectX 9 graphics with 128 MB memory (in order to enable Aero theme)
Internet access (to download the Beta and get updates)
Now, for the keygen. You will have to go through the sign up for beta in the normal way to uinderstand what I mean. Once you get to the "Windows 7 Beta xx-bit Product Key" page which you should print and keep, here is where magic happens. You need another key? JUST PRESS THE BACK BUTTON ON YOUR BROWSER!!!
Ya, basically, it repost you previous request and give you yet another set of keys for the xx-bit product you just selected. Technically, this is not illegal since this is beta anyway. So I advise anyone who read this, PLEASE DO NOT ABUSE this system. Just make a few key if you need to install a few copies of Windows 7. Microsoft has been nice to provide the beta for no charges so let's not make them pull the beta offline because of this.
BTW, I think I should alert someone from Microsoft about this... But who? :)
P.S. I am also open for employment by Microsoft. Please contact me... :P