They also have served as trackers, messengers, sled pullers and deliverers of first aid.

WSJ: Letting Slip the Real Dogs of War

Many are important deliverers of services, especially in developing countries.

ECONOMIST: Citizens�� groups

From the biggest ad agencies in the world to the most cutting-edge digital idea shops and deliverers, digital media has become one of the most cost-effective methods of reaching an audience.

FORBES: Think More, Think Local