Honestly.. I'm a bit torn about this.
I like the Karma option, because not only does it have the ability to boost someone's ego, after they've done something good. It /can/ give you an idea of who's helpful. People with like, 80 Karma have obviously done something right to get to that point. Plus, I feel good after I've clicked someone's nuzzle button. I feel like I've done something nice xD
But I don't think there should be a bite button.. It will lead to people getting bullied because of their negative Karma number and such. Whether they did something to deserve it, or not... I think you should only be able to give Karma, not take it away.
I also like the idea of being able to turn it off and on. This way, if someone just doesn't want anything to do with the Karma drama, they can just shut if off. Then they won't have to worry about whether their Karma has gone up or down today, and they won't have to feel bad about themselves if someone bites them lol
Karma can be good and bad.. in the end, I voted no. I like to give out Karma. I think it's a nice gesture to nuzzle someone :3