Five Largest Nations by Population or Active Users, early 2010

1. China, 1.3 gigacitizens
      geographic single-party “people’s republic”, president Hu Jintao and premier Wen Jiabao
2. India, 1.2 gigacitizens
      geographic federal republic/parliamentary democracy, prime minister Manmohan Singh
3. Facebook, 400+ megacitizens
      networked-membership corporate principality, chief executive Mark Zuckerberg
4. United States, 308 megacitizens
      geographic federal constitutional presidential republic, president Barack Obama
5. Indonesia, 231 megacitizens
      geographic presidential republic, president Susilo Bambang Yudhoyono

Good luck, Mark!