Having a problem with a neighbor's dog? One that barks, barks, and barks, escapes from their owner's yard and causes problems, or a dog you're concerned is dangerous? A simple talk with the dog's owners could prompt them to fix their backyard fence, keep the dog indoors, or start dropping their pooch at doggie daycare. If discussions don't do it, enlist the help of an experienced local mediator (many community mediation groups handle disputes involving dogs).
You may also be able to get help from your local animal control agency or the police. Finally, if nothing else works, you can sue the owner of a nuisance dog in small claims court.