University of California
Ucmp: Aves Life History and Ecolog
University of California Berkeley offers a good discussion of the natural role that birds play and the importance of this role to man.
US Fish and Wildlife Service
U.s. Fish and Wildlife/agents Target Illegal Bird Trade
A good article on an issue that exemplifies man's exploitation of some bird species.
US Fish and Wildlife Service
U.s. Fish and Wildlife: Migratory Bird Treaty Act
A good article from the U.S. Fish and Wildlife Service on those birds that are protected by some legislation. Also includes some information on the hunting rules for several species.
Other
Feather Site: The Poultry Page
A good description of all of the different types of poultry that are raised in the U.S.
Other
American Egg Board/the Incredible Edible Egg Site
One of the major uses of birds by society is for food production. This site delves into our use of eggs.