Freicoin
Freicoin is "Bitcoin with demurrage".
It is an alt chain with the design goal that holders of the coin will have negative interest rates, as a means to redistribute wealth from rich people to poor people. Fees are taken for holding coins and distributed to miners.
The major issue with Freicoin is that of incentives - why would someone choose to hold a Freicoin and incur demurrage, where he can just hold Bitcoin instead?