ImaginaryCountries

Europe

• Belsornia -- From which Elisaveta of the Chalet School hies -- Somewhere between the Anschluss and the Soviet Union, near Mirania.
  
• Guilder -- from The Princess Bride, next to Florin.
  
• Florin -- from The Princess Bride, next to Guilder.
  
• Mirania -- see Belsornia.
  
• Latveria -- small Eastern European country ruled by Doctor Doom, of Marvel Comics fame.
  
• Symkaria -- adjacent to Latveria, same source.
  
• Novistrana -- from RepublicTheRevolution? (see http://www.novistrana.com/). Formerly part of the Soviet Union. No location given other than that, although there is ethnic unrest in the south, and all the names are very Russian, which suggests the Caucausus.
  
• [Ruritania]
  
• [Lyonesse]
  
• [Orsinia] -- Eastern European country from various of Ursula le Guin's books.
  
• Tigana (~Italy), Al-Rassan (~Spain), Arbonne (~southern France), Batiara (~Greece), the Sarantine Empire (~Byzantine Empire) plus others... -- Guy Gavriel Kay's parallel-world Europe-equivalent. [GGK's website]
  
• Vulgaria -- from Chitty Chitty Bang Bang. Mountainous Eastern European Country ruled by a despotic Baron and his spoilt wife.
  
• Elbonia
  
• Freedonia and Sylvania, from Duck Soup
  

Americas

• San Theodoros -- South American dictatorship to which Tintin the boy reporter travels (and at one point is inadvertently appointed a colonel in the army of).
  
• Nuevo Rico -- hostile neighbour of San Theodoros, same source.
  
• Corquidicolandia -- see http://www.srcf.ucam.org/assassins/archive/special/generale03/
  
• El Dorado -- the land of gold from South American legend, becoming adopted into Spanish folklore and European Literature, including Candide by Voltaire. See http://www.factmonster.com/ce6/history/A0816958.html for more historical information.
  

Asia

Africa

• Wakanda -- home to (and ruled by) T'Challa (the Black Panther, a sometime member of the Avengers), and source of the sound-absorbing metal Vibranium, in the main Marvel Comics continuity.
  
• Genosha -- (Marvel Comics again) an island off the coast of Africa, where mutants are used as slave labour by the non-mutant population.
  
• Kumbolaland(sp?) - visited by War in Good Omens (Terry Pratchett and Neil Gaiman)
  

Rest of the World

• San Seriffe -- a small fictional island created by a (real) Guardian reporter for purposes of getting a delegates' pass at an international conference.
  
• [Atlantis] -- 'nuff said.