How about something like this collar? It sprays citronella when they bark. Dogs HATE the smell. It's a bit pricey though--$40.00 for collar and $9 for spray refills. I know people that have had success with it. Pups must be 6 mos. or older though.
"If you want to stop your dog's excessive barking effectively without hurting him with a shock collar, try this Petsafe/Premier GentleSpray Citronella Anti-Bark Collar.......The GentleSpray Anti-Bark Collar is a much more humane and effective nuisance barking solution, delivering a harmless burst of citronella to interrupt your dog's barking. Your dog will quickly and painlessly learn that there is a consequence for barking. He should completely assimilate to the collar within a few days. This harmless spray conditions your dog to behave properly by working on four of his five senses: he hears it, feels it, sees it and smells it."
Gentle Spray Anti-Bark collar