The Intergalactic Time Bank is the universal currency used by all Hitchhikers. It is unlike any currency used on earth - not having any value or utility whatsoever.
Hitchhikers everywhere exchange these tokens as mere gifts - more a symbolic ritual and act of joy than a payment.
The greatest difficulty most users of the currency have is the guilt they feel paying for services provided by other Hitchhikers. Huge positive balances naturally accrue, where Hitchhikers give their services freely while failing to allow others to do anything for them in return.
Luckily this was a know problem of earlier Time Banks, and the designers of the Intergalactic Time Bank, addressed this issue by making it easy for users of the system to give their tokens to other Hitchhikers - or the projects they support.
This unique feature - which was the initial reason for the invention of the improbability drive - solved all the universes financial problems overnight - though there were some small if unpleasant side effects.
Consequently a great deal of time was saved, in which instead of the interminable "I'll pay", "No I'll pay!" disputes, Hitchhikers were more than happy to use the improbability drive to magically vanish large sums from their account to unkown and very improbable destinations.
The productivity boost this gave the intergalactic economy easily paid for the vastly increased bureacracy, and Mining Costs associated with the new currency.
# See also - Voz and Time Bank - Course Structure - Global Time Bank and Intergalactic Time Bank - Galactic Time Bank - Pangalactic Timebank