Can anyone advise me how one would go about creating there own domian extention such as .stu

Thanks,

They control that sort of thing, you'd probably get an answer by talking to them about it, but don't hold your breath, I'm sure it'd be an expensive proposition EVEN if they agreed to do it --

http://www.internic.net/

I doubt Internic would do such a thing based on one request. Maybe try: http://www.new.net/ but I highly doubt you will get such an extension maybe if 10 million people requested it then maybe.