Ladonia

Artist Lars Vilk decided one day to build a city out of driftwood and nails. The sculptures, titled "Nimis" and a stone fortress titled "Arx", all live inside the Kullaberg nature reserve in Skåne, Sweden. It wasn't long before the Swedish government saw the sculptures and determined that they were houses and not scuptures. Due to the fact that they were in a nature reserve the government demanded that they be taken down. Instead of taking down the sculptures as requested, Vilks declared the region -- "Ladonia" -- a micronation in protest.

From what I can find out about Ladonia it has already had a storied past. In 2002, 4,000 Pakistani refugees mistook Ladonia for an inhabitable country and applied for asylum. Sadly none were given residence. :(

In 2006, the Pirate Bay-funded Armed Coalition Forces of the Internets declared mock-war on Ladonia, demanding that its government repeal copyright laws and recognize the rights of intellectual property pirates.

For a mere $12, you can become a citizen of Ladonia, joining its current membership of over 14,000 individuals.

Presumably, membership grants you the right to move into Ladonia in the event of an apocalypse, or at least blueprints for building your own version of Nimis.