on youtube, for the volume control, there is a little scroll wheel-- digital dial thing.  This would be nice for the Karma rating so that you can easily scroll it up or down to higher and lower numbers very quickly.  I think only being able to change it slowly, one number at a time, affects peoples decision to rate.  Also, being able to quickly scroll through numbers would produce much more polar ratings which would affect the average rating at a greater rate, so we would start to see some actual results build up quite quickly.  It doesnt feel like Im doing anything by rating someone a 49/51 or even 45/55 for that matter.  If I could quickly set a little digital dial to 10, or 90, or 75. or whatever, I would be much more inclined to use the Karma system.