Why I think another feature is needed:
There are currently 2 primary methods of gamification for the site: Reputation and Badges. (Hats seem like a tweaked form of badges, and as they're seasonal, don't they go away soon?...)
Reputation most strongly incentivizes good answers, (which is certainly valuable), then good questions (also valuable, but perhaps gamed too much,), and to a much smaller degree, accepted edits.
Badges, once earned, are kept forever, and repeated earns are nice incentives for long-running expert users, but again primarily reward the questions and answers.
But what have you done for me lately?
The current system mostly rewards putting in some positive effort to ask/answer questions, then one may go away as time accumulates even more points as people find answers to their questions from material you've posted. How do we reward recency? Thanks for everything you did a year ago, but where did you go? Have you been helping the site? Reviewing stuff maybe? Letting others get the easy quick answers mostly, but voting up stuff that's good and down stuff that's bad?
Are you a good Stackoverflow citizen?
The current system doesn't reward good comments (particularly on why questions or answers are bad) beyond the localized upvotes on the comment.
I think it would be very valuable to the site to give an indicator of the recent less-tangible user contributions to the quality of the site (and thus an indication of the value of the user to the health of the site).
Have qualified programmers with good intentions a good enough reason to stick around and learn the ropes?
I personally know qualified programmers with good local reputations that have been turned off by the difficulty of gaining acceptance and learning the way the site works. I think they're quite willing to take their lumps until they get it, but they get discouraged in the learning process that gives them little to no recognition for their recent efforts. We need a reward system that encourages them to stick with it until they get it.
The question is, how do we fill these gaps?
My favourite idea is a health bar based on activity, which I elaborate on in an answer below. My next favourite idea is a balanced scorecard (see Wikipedia, or just about any edition of the Harvard Business Review.) I'll get around to making hypotheticals on that eventually.
This question is made in the spirit of helping my favorite resource for canonical, if unofficial, specific programming advice. Recommendations should be possible. Stackoverflow can determine if they are practical.
PS (to delete some time after seeing this question's reception...)
Thanks!! I anticipate this might not go over well, but please explain downvotes. I have carefully examined all questions for overlap, and I think this question is disjoint from the others I've seen along these lines. I've been trying to break into the stackoverflow community for some time (always frustrated by not being able to thank good answers with an upvote) but only recently began earning reputation. (Never asked questions because I'd always find the answer on my own, never good enough to answer questions until recently.) :)