Principality of Sealand, photo by misterbisson (has some geodata on the Principality)
I learned of the Principality of Sealand in a 2000 Wired article. Kind of an interesting, real life cyberpunk scenario that I recall made me think about the nature of nations in the future.
Apparently on Friday, the seat of the throne of King Roy Bates (and site of an offshore datahaven) was seriously burned in a fire. I assume that Slashdot and Digg will overwhelm these links today.