[busyant]

> I don't claim to have all of the answers, but a decay function seems quite obvious to me.

I don't have a super-informed opinion here, but a decay function sounds reasonable. I'd also suggest that the decay be uncoupled from the user's karma (i.e., the user keeps his/her karma, but the value of the votes decay over time to make way for changes in technology). I don't claim that this is a well thought out idea, but at first blush, it seems reasonable. Also, I just don't give a shit what my karma percentile is.

Finally, FWIW, I find SO ~85% useful and ~15% problematic. And I feel like sometimes we fixate on the 15% without acknowledging the genuine utility of the 85%.