Request Country Registration Whitelist/blacklist

According to Stop Forum spam the marity of spam comes from China and Ukraine. I also noticed a ton of spam from Pakistan on a forum i manage.

It would be awesome if you could add a whitelist/blacklist that allows/disallows certain countries from registering. The country list should be checkboxs (so we can select easily) and rather than rely on a local database (GeoIP) that we have to keep up to date it should use one of the online ip query services.