Both coin programs I'm proposing, would need to include the bitcoin like program, and an exchange. There is not currently an exchange attached to any version of bitcoin to my knowledge. I'm working on a distributed exchange outside bitcoin (
https://github.com/macourtney/Dark-Exchange), and you could use a centralized exchange like MtGox or TradeHill, but that would defeat the decentralized aspect of a bitcoin like program. More work and though is needed in this area.
removed option expiration.
How about a very limited type of exchange within the main chain:
Every block contains a price inserted by the miner. A block solution must contain a signature on a standard contract using the coinbase output keypair. The contract is an option to:
buy at the quoted price plus a standard spread (e.g., 1%)
or
sell at the quoted price minus a standard spread
an amount of the underlying commodity equal to the block reward. The option can only be exercised by solving a block with this block as its parent. To exercise such an option, a miner must set a special flag in the next block. The two miners have to find each other and settle up (no need to specify how) before either can claim his block reward. They must both sign something using their coinbase keypair and submit the signatures to the network before the network will recognize their block rewards.
Perhaps the spreads don't have to be standard, the contract can specify any prices straddling the quote. Miners would be motivated to offer good terms in order to encourage the network to accept their blocks and thus validate their rewards.