You are guaranteed to be able to take the following (if they are not chosen my another new player):
Bavaria
Hanover
Belgium
Argentina - Dannaroo (1st choice) <pending>
Switzerland - Dannaroo (3rd choice) <pending>
Netherlands - Sadko (1st choice) or Dannaroo (2nd choice) <pending>

The following are already taken:
United Kingdom - Pasta Sentient
USA - Byrd Man
CSA - AegonVI
Prussia - So Boerd
Austria - Ampharos
France - solamelike
Russia - thorgili
Ottoman Empire - Kho
Spain - aladdin_sane
Italy - NarcolepticSailor
China - MagnificentOne
Japan - Sovi3t
Sweden - Dedonus
Mexico - bigscreech
Romania - emmy1320
Greece - duck55223
Brazil - Rare
Colombia - Giant
Siam - Heyitsjiwon
Denmark - bahamet1

You may ask for a nation that is no listed on this list. However, the more obscure or insignificant, the less likely it will be accepted.