Planet with Pop 8+, Gov 3+, Tech 9+
Arriving on planet, the players find the local government has instituted a unique form of currency: biomoney. In order to encourage spending and increase the velocity of money (the number of times a unit of currency changes hands per unit of time), al l currency is alive. To keep it alive, it must be kept next to the skin . However, the money gradually becomes allergic to the person who is carrying it, so it must be spent within 7 days or it dies and is no longer legal tender.
All transactions of 1000 credits or less must be paid for in biomoney, and the first 1000 credits of all salaries and compensation is paid in biomoney. This means the players will have no choice about using biomoney if they visit the planet (as a good GM will insure happens).
What the currency looks and feels like is up to the GM, though it is suggested that it should be rather disgusting (that encourages people to spend it as quickly as possible).
1) One of the characters turns out to be allergic to the biomoney and becomes deathly ill with a nasty rash. However, money kept next to his skin does not die, even after seven days. Complications include cruel fellow players, criminals who want to exploit the player to hide their money, the planet's currency police, etc.
2) A local underground group contacts the players and asks them to take a sample of the biomoney off-world for analysis. They are convinced the money is poisoning people, but the government is covering it up. The truth of the matter is up to the GM.
Note: This is really more of an encounter than a true adventure seed. It was inspired by a description of a Traveller gaming session I read years ago, where one of the things the players encountered was, I swear, an alien animal that looked like a n "inside-out rat." My immediate thought was, "What if the players were forced to handle inside-out rats on a regular basis?" I know, I'm sick, but then again, most GMs are...