First off let your neighbors know you're aware of the problem and searching for a solution without resorting to electronic collars. Sometimes letting them know you're aware and trying to do something is all they need.

Second, what breed are they? Some breeds are simply barkers because they were bred to do so. Some breeds respond to training that if they bark, their play time is over. They soon learn to play without barking, because as long as playtime remains bark-free they can continue to play. It works on some dogs, but not all. The barking breeds have a really hard time with this concept because its inbred to bark when excited.