While reading this question, Which accounts have more questions than answers?, I started wondering what ways are there that we can measure participation more accurately than reputation.
I've always been skeptical that a user's reputation score actually reflects their "reputation." That is your level of knowledge and ability to ask/answer questions may not be correlated to how well you "play together in groups," as they used to say in kindergarten.
On the theory that, if you can't say something nice about someone, you shouldn't say anything at all, I wonder if the ratio of upvotes to downvotes may be a better indication of your "plays well together" score than your reputation. Another potential measure may be the ratio of upvotes to downvotes on your own questions. Or flags to votes?
What other metrics, or would any of these metrics, be useful to expose for users on the site?