- Na-Griamel, in which Jimmy Stevens tried to break Espiritu Santos away from the newly-independent Vanuatu (previously the New Hebrides);
- Galt's Gulch Chile, a Rand-influenced plan to build a hideaway in Chile (how it fell apart, and plans to resurrect it);
I'm sure there are more. But the latest one has an interesting bent; it is based on a small (tiny) plot of land between two countries that don't really like each other (Croatia and Serbia), which due to the irregular border, neither country lays claim to. Have a look at the simplistically-named Liberland (official website; Wikipedia article).