|The Bristol ten pound banknote|
From the BBC:
It is a direct assault on global trade. The city of Bristol has launched its own currency, which cannot be used in Bath, never mind Berlin or Bombay.
More than 350 firms in the city have signed up, making it the UK's largest alternative to sterling.
Unlike previous schemes which have relied on paper, the Bristol Pound can be used online, even by mobile phone.h/t Tyler