What if you wanted to decrease anonymity?
Trying to build a centralized credit system would require a mint, which is why this protocol was build in the first place. We don't want mints and on top of that we don't actually need mints for most functions. I would suggest you take a look at those whole new possibilities that come along with this protocol, such as coloring, escrow services, etc and forget all about the old-fashioned and in many cases incapable credit scoring system. Or, if you insist, try to make use of the all-public transaction log after you have associated an entity with a public address, maybe with a micro-payment or the such.