I'm having luck this summer with sheer bribery, if that helps! I started making DS8's allowance dependent on behavior even more than on chores. As soon as he starts picking on his sister, I ask him if it's worth a quarter (how much he will lose if he does it) and he decides it's not, and he stops. It's working for fighting, rudeness, and bad attitude in general. He can also get a quarter back, or an extra one, for good things that come along.
I'm actually quite a fan of the Nurtured Heart thing, just for the record, but I'm not home most of the day and just can't make it work right now.
