I think this is a good idea. I've actually thought of something similar myself. Why not have each person's reputation be based on a variety of attributes -- discussion forum insight, financial reliability, technical expertise, etc.

This could eventually replace the credit ratings infrastructure of experian, equifax, etc.

Ideally lots of sites would participate -- e-commmerce sites could rate you as a customer (headache free, not trying to cheat on promotions, etc.), kiva could rate you, etc.

It would also be great if reputation could be tied to biometric data to prevent transfer and fraud.

Such a system would ideally be open, cryptographically sound, and free.

I think that a properly designed system would end up removing lots of the transaction costs associated with more mainstream reputation systems.