I'm pretty sure that almost anyone on NS who actually uses the karma system simply gives the person a 10 or a 0. I think just giving a thumbs up or a thumbs down would be a much simpler system. I've been on another forum that did this and you were actually able to thumbs up or down on that person more than once. It was caped and on rating per day but lets say somebody gives you good advice so you give them a thumbs up. next week that guy says something awesome in the forums and you go to thumbs up but you've already thumbs uped that person so now you can't.