I guess I'm not understanding what reputation you're trying to catalog then, if not "is this coin valuable or not?" Can you elaborate on that?
Oh sorry,
A system where each user would have reputation, similar to what you have on a forum. People could have some minimum level of trust and know whose person to approach if they wanted to buy or sell something. For example, you wouldn't lend your bitcoins to a user with a bad reputation, however if you knew someone was a respectable user you probably are more inclined to loan then (assuming they're paid with interest).
Hope I explained it clear enough now