my buddy's dog got lost once. turns out he was stuck in somebody's window well, and couldn't get out.
this same friend of mine also found a dog dog running around that looked pretty thin and scared. he caught the dog, fed it, and took it to the vet the next day. turns out the dog had one of those microchips in it, and they were able to contact the owners. the dog had been missing for 12 days, from a town about 17 miles away.