I wonder if the leaderboard should be ranked by karma x average comment score.

That makes sense; put differently it would be roughly karma^2/comments^1

And right now the settings are karma^1/comments^0

To generalize, one way or the other you have karma^x/comments^y which looks strikingly similar to points^x/time^y

Why not tinker with different variations until you get a couple of (probably non-integer) exponents that generate a leaderboard you think best represents the ideal character of the site, the same way you tinker with time gravity to alter the frontpage and comment pages?

I don't think it's a bad idea to have more than one table on the leaderboard. Having one "overall" table is nice, but having a bunch more stats would be fun.

Ok, the leaders page now shows both total karma and the average for recent comments.

It would be cool if you could choose the column to use for ordering.

Rather enlightening though... I found myself instantly hitting the comment threads of users with recent comment averages > 10.

That would heavily weight against simple comments, which might be a good thing.

It might be better to hurt the leaders based on the ratio of <=0 comments.