http://nokia.dogtoe.com/
I used this to upgrade my N80 firmware today and it works great, use at your own risk however.
This is Nokia software and ovbiously not for public distribution, that said Nokias policy of only providing free firmware upgrades if you purchase the phone in the country your getting the upgrade is pretty retarded IMO. If you have a Nokia phone which isnt actually released in that country and you are trying to get a firmware update then your crap out of luck all together and you would have to resort to this or sending your phone overseas.
That is until operators start supporting FOTA, some of the new Nokias now support this but no operators AFAIK.