As far as I know Andrew, RC and myself are the only ones with karma disabled.
Add me to the list.
I know the intentions are good but I never felt comfortable receiving or giving karma (though I gave a spammer negative karma not too long ago). No matter how you twist and turn it, it reminds me of a popularity contest.
We had a similar feature at my other forum some years ago but it was disabled because it actually caused forum drama. Doesn't seem to be the case here though.