From bird-washing machines to clean spilled oil from feathers to hen-sitting services, the avian innovations here are all for the birds in our world.

Human beings are fascinated by their feathered friends. Pigeons have been used to fly messages from one place to another, and some parrots live to be a hundred years old. While we more often choose dogs or cats as pets, birds can be great pet-friends -- and friendship is one avian innovation that is definitely not just for the birds.