IIRC Sealand sells post cards, as part of its general merchandise thing (along with nobility titles). Not sure about stamps though.<p>Another quasi-governmental curio is that, again IIRC, Spain has <i>several</i>, maybe even a dozen or something, local currencies. All being traded just fine in their communities. (I think the US also has or had at least a couple, though those were essentially just checks of some co-op banks, and thus nothing new in the country.)<p>Also I remember reading about a currency established by a gang that controlled a part of a city—and which currency ended up being used more actively in the city than the country's currency, because it was more stable. Don't recall where it was: possibly northern Africa, maybe Ethiopia or Eritrea.