Losing a pet is every pet owner’s worst nightmare. Before it happens to you take the time to get your pet micro chipped at your local vet. A study of more than 7,700 stray animals at animal shelters showed that dogs without microchips were returned to their owners 21.9% of the time, whereas microchipped dogs were returned to their owners 52.2% of the time. Read more about micro chipping here.
Some tips are to post missing pet signs around your neighborhood and on bulletin boards at local vet offices. You can also post classified ads in the local papers. Also be sure to check the found sections of any newspaper or online classifieds as well as the pet section for any found animals. There are a lot of links here so if you are short on time focus on Campbell yards sales and Craigslist! Also search on foot or in a car. 90% of pets are found within two miles of where they were lost.
About.com: Find Your Missing or Lost Dog (Also good for other animals)