Update: See: Grapevine for reference implementation and Hacker News.
Grapevine is a distributed protocol for replacing twitter like systems. It is composed of nodes that add a proof of work over a message and nonces from previous nodes, so the proof of works stack up as messages pass through nodes. Messages with a higher total cost have a higher probability of being forwarded to the next node. Individual nodes decide the cost of the proof of work they add to the message. This decision can be manually made, or with algorithms like page rank, word vectors, grammar checker, or some other algorithm. This is up to the node operator. In the case of page rank, the rank of the message could be determined relative to some other content such as the Bible. Holy messages would then get a high cost proof of work. A proof of work algorithm that is memory bound should be used. Messages should be limited in size such that they fit inside a single packet. This protocol could be implemented as a UDP based system. This protocol is a good idea because it is distributed and democratic.