You've got the point. I imagine that HN karma is a system very close to the ideal. At first, it would only one things: an interface to the real world. I mean, people breaching contracts and people fulfilling them in the real world should be thrown into this system, and the real world people (which should not need to make a special type of digital contract or something, because they already have their own contracts that should be valid) must be able to use this database of ratings to make decisions.