I have a conceptual overview at Retzle Conceptual — Bitbucket of an app I built in Scala w/ Cassandra which is not done yet and closed source atm. It would be that design I would follow, but it is dependent upon upcoming features like messaging. It is also dependent possibly upon how easy it is for me to programmatically also determine the amount the app is making from use so it could be distributed as well. Like the other poster said, if the coin is not natively divisible then it would be the app’s responsibility to maintain the state of accumulated karma on a per user basis that could be “cashed out” at whole coin amounts.