have you ever seen the dog whisperer? i don't agree with some of his methods but i do use one of the noises he uses to correct or stop a behavior. its kinda like a 'pssstttt" sound. if you watch the first video on this page he makes that sound a lot
http://channel.nationalgeographic.co...preview_1.html . i use that sound on morgan to correct or stop what she is doing if i don't want her doing it and she responds very well to it.
also, there is a collar that the dog can wear a collar that sprays citronella at them whenever they bark.
http://www.mightypets.com/product.asp?3=541 i know a couple people that have used this collar on their dogs and it stops the barking right away. the spray does not harm your dog in any way.