Why not register a domain?
They're fairly cheap and doing so will guarantee that you don't clash with anybody else (or at least give you the satisfaction that if a clash does occur, it's the other person who will have to rewrite their code).
Either register your own name, or try to make up a name that you may use as the basis for a business at a later date.
bernard.surname.net
madeupname.net
This will cost you less than 10GBP per year.
Personally, I'd go for the made up name approach, as it's likely to look more professional (unless you choose something really strange).
An added advantage is that a lot of domains will come with email capabilities, giving you a better email address than bernard.surname@hotmail.com.