hee - we have a whole series of jars, Lovemydd! ours work the other way (it's a fine, rather than a reward) but they've been great. we have the Little Jar of Hate, the Little Jar of Screams and recently, the Little Jar of Profanity (though that one is only affecting DH so far!) and after over a year of implementation, there's only about $0.65 in each of the others... they've really, really worked.
we also have one called the Big Jar of Solutions where i record every time DD comes up with an idea vs. makes a complaint, and we read those out on New Year's Eve - it's fun!
best of luck with everything - i'm so pleased to hear you and your DD had a positive chat last night... i hope things improve for you - this is such a tough one.