Proposed simple REST (and OAuth) based standard for financial transactions
wiki.github.com
wiki.github.com
So, for example, the URL http://eepay.com/usd/10/agh38hj3 would represent a $10 USD note, payable by the entity that issued it.
Ownership of a particular currency "note" would be handled via a private key. In other words, the individual in possession of a private key for a given URL would be considered the "owner" of that note. With that private key, one could either redeem the currency in question or transfer ownership to someone else. Transfer of ownership would be handled via a secure handshake, in which the new owner of the note is given a new private key, which can then be verified.
Obviously this is all very low level, so actual transactions would abstract away most of this.
The advantage of this type of currency would be that it is anonymous and doesn't require a whole lot of verification information for every little purchase. This would make it ideal for microtransactions, or for transactions where you wouldn't want to reveal your identity.
The disadvantage is that it would be a challenge to keep private keys secure. Another obvious disadvantage is that such currency would only be successful if it was backed by a highly trusted institution. There are other challenges and disadvantages to be sure.
If you can't solve that problem, your economy is going to have more liquidity than real assets. It's a hard problem.
Much respect for Pelle. But this won't fly until that problem is solved.
And, isn't that level of assumption a good thing for comprehension and interoperability?