The MakerDAO system (which I contribute to) issues a token called dai against Ethereum token collateral. The dai token is meant to have low volatility measured

The MakerDAO system (which I contribute to) issues a token called dai against Ethereum token collateral. The dai token is meant to have low volatility measured against fiat money. There's roughly 9 million USD worth of outstanding dai tokens at the moment, all representing a form of debt to the MakerDAO system with ETH as collateral. The first version uses only ETH as collateral, with a high degree of overcollateralization. The next version is supposed to use different collateral types. One interesting type of collateral is tokenized gold, as will be issued by the Digix project.