I came across this fabulous article that discusses reward systems and thought it may help anyone who is currently implementing one at home. It discusses how reward systems can be used to reinforce positive behavior and will hopefully diminish specific negative behaviors. The article also gives several suggestions for those who have tried to implement a reward system that did not work.
Happy reading!
http://www.slate.com/articles/life/family/2010/03/if_youre_good_ill_buy_you_a_toy.html