Dublin is cheaper than London, boasts low corporate tax rates, and everybody speaks English. Its "Silicon Docks" neighborhood houses tech giants Google, Facebook, LinkedIn, and Zynga. Last year Twitter announced that it was opening its third international office (after London and Tokyo) in Dublin, making the city its European headquarters. The annual Dublin Web Summit is one of the fastest-growing tech conferences in Europe.
CEO Mark Zuckerberg would like to reach the country's 513 million Internet users. Too bad local entrepreneurs have beaten him to the punch.