Here is an idea: a world-wide, distributed, decentralized supercomputer that would use bitcoin's block hashes as timetamps for synchronization of processes. Such a computer would have quite a low ticking clock (only 6 ticks an hour in average), but it would me massively parallel.
Well, I was thinking about the problem of light clients and having to trust a blockchain server, and I thought, wouldn't it be great if, instead of interrogating a single blockchain server about some transaction's validity, wouldn't it be great if the bitcoin network
as a single entity, could respond to such requests with a cryptographically secure and verifiable result.
It would be like asking an oracle: "O Bitcoin Network, my buddy Tom wants to pay with this transaction 0xblahblahblah. Canst thou tell me if I should accept it?"
In a certain sense, this would be treating the bitcoin network as a computer, or at least, a computing machine. Once you're adequately connected, the system would be quite secure I think. Being massively parallel would help with verifying many simultaneous transactions. I got as a far as thinking that this ComputingMachine would merely require an authoritative list of transactions, and then I thought, oh, like a blockchain :-/
