neighborhood forums for lost and found pets?

Google "Lost Pets" - there's a multitude of websites where you can register your lost pet, or one that you found - as well as search local listings.

Contact local shelters, veterinarians, and police departments, as well - whether a pet is lost or found, these are usually the first numbers that are called, and the best for reuniting the pets with their families.

http://www.craigslist.com/