The Haynet (links to dozens of equine-related Web sites)
International Museum of the Horse (informative link to a museum dedicated to the horse-online)
"Fossil Horses in Cyberspace" (quality, interpretive virtual museum exhibit created by the Florida Museum of Natural History, University of Florida, Gainesville)
"Talk Origins" (a Usenet newsgroup devoted to the discussion and debate of biological and physical origins. Detailed information about the evolution of the horse)
Conquistador Magazine (a private site, not associated with BLM)
Bureau of Land Management (adoption details, history, links)
Wyoming Bureau of Land Management (Wild Horses)
Assateague Island Wild Ponies (Assateague Island National Seashore)
Institute of Range and the American Mustang (operates and supports the Black Hills Wild Horse Sanctuary near Hot Springs)
"KBR's World of Wild Horses and Burros," Page 3 (wild horses by state and area)
Pryor Mountain Wild Horse Range (Montana/Wyoming)
Animal Welfare Institute (education/research organization)
International Society for the Protection of Mustangs & Burros (established 1965 -- the oldest wild horse and burro protection organization in the world)
KBR Wild Horse and Burro Information Sheet (wild horse and burro groups and registries)
Society for Animal Protective Legislation (lobbying arm of the Animal Welfare Institute)
Wild Horse and Burro Freedom Alliance (coalition of animal welfare organizations devoted to wild horses and burros)
"Breeds of Livestock: Horses" (compiled by the Department of Animal Science, Oklahoma State University)
"Horse Breeds of the World" (a mega list)
Veterinary Genetics Laboratory, University of California, Davis (information on horse genetics, gene mapping and horse typing services)
"Equine Identification: Colors and Markings" (Equine Research Park, College of Veterinary Medicine, Cornell University )
"Horse Color Chart" (The Horse Lover's Corral)
"Markings of the Horse" (The Horse Lover's Corral)
Horse Anatomy (The Horse Lover's Corral)
"Horse Dictionary" (The Horse Lover's Corral)
"Interesting Horse Facts" (The Horse Lover's Corral)
Here is a list of books you might find interesting:
Amaral, Anthony. Mustang: Life and Legends of Nevada's Wild Horses. Reno: University of Nevada Press, 1977.
Barclay, Harold. The Role of the Horse in Man's Culture. New York: J.A. Allen, 1980.
Berger, Joel. Wild Horses of the Great Basin: Social Competition and Population Size. Chicago: The University of Chicago Press, 1986.
Budiansky, Stephen. The Nature of Horses. New York: Free Press, 1997.
Clark, Laverne Harrell. They Sang for Horses: The Impact of the Horse on Navajo and Apache Folklore. University of Arizona Press, 1983.
Clutton-Brock, Juliet. Horse. London: Eyewitness Books series, Dorling Kindersley Limited, 1992.
Denhardt, Robert M. The Horse of the Americas. Norman: University of Oklahoma Press, 1947.
Dobie, J. Frank and Charles Banks Wilson (Illustrator). The Mustangs (Reprint Edition/Paperback). Austin, Texas: University of Texas Press, 1984.
____________, M.C. Boatwright, H.H. Ransom (ed.). Mustangs and Cow Horses. Dallas: Southern Methodist University Press, Texas Folklore Society, 1940.
Edwards, Elwyn Hartley. A Spirit Unbroken. Stillwater, Minnesota: Voyageur Press, Inc., 1995.
Ewers, John C. The Horse In Blackfoot Indian Culture. Smithsonian Institution Bureau of American Ethnology - Bulletin 159. Washington, D.C.: United States Government Printing Office, 1955.
Farley, Steven. Wild Spirit. New York: Random House, Inc., 1999.
Green, Ben K. and Joe Beeler (Illustrator). A Thousand Miles of Mustangin'. Silver City, New Mexico: High-Lonesome Books, 1998.
Groves, Colin P. Horses, Asses and Zebras in the Wild. White River Junction, Vermont: Ralph Curtis Books (Chelsea Green Publishing Company ), 1974.
Henry, Marguerite. Mustang: Wild Spirit of the West. Rand McNally, 1974.
Jackson, Jaime and Larry Lindahl (Illustrator). The Natural Horse: Lessons from the Wild for Domestic Horse Care. Northland Publishing Company, 1992.
Kirkpatrick, Jay F. and Michael H. Francis (Photographer). Into the Wind: Wild Horses of North America. Minocqua, Wisconsin: Northwood Press, Inc., 1994.
Lester, Julius and Jerry Pinkney (Illustrator). Black Cowboy, Wild Horses: A True Story. New York: Dial Books for Young Readers, 1998.
MacFadden, Bruce J. Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. New York: Cambridge University Press, 1992.
Medicine Crow, Joseph. From the Heart of Crow Country: The Crow Indians' Own Stories. New York: Orion Books, 1992.
Osborn, Henry Fairfield. Origin and History of the Horse. New York: The New York Farmers, Metropolitan Club, 1905.
Roberts, Monty and Christopher Dydyk (Photographer). Shy Boy: The Horse That Came in from the Wild. New York: HarperCollins, 2000.
Ryden, Hope. Wild Horses I Have Known. New York: Clarion Books, 1999.
__________. America's Last Wild Horses (30th Anniversary Edition). New York: Lyons & Burford, 1999.
Scanlan, Lawrence. Wild About Horses: Our Timeless Passion for the Horse. New York: HarperCollins Publishers, Inc., 1998.
Sponenberg, D. Phillip. Equine Color Genetics. Ames, Iowa: Iowa State University Press, 1996.
__________ and Bonnie V. Beaver (Contributor). Horse Color. Philadelphia: Breakthrough Publications Inc., 1998.
Spragg (ed.), Mark. Thunder of Mustangs, Legend and Lore of the Wild Horses. San Francisco: Sierra Club Books, 1997.
Symanski, Richard. Wild Horses and Sacred Cows. Flagstaff, Arizona: Northland Press, 1885.
Thomas, Heather Smith. The Wild Horse Controversy. New York: A.S. Barnes and Company, 1979.
Waring, George H. Horse Behavior: The Behavioral Traits and Adaptations of Domestic and Wild Horses, Including Ponies. Noyes Data Corporation/Noyes Publications, 1983.
Webb, Walter Prescott. The Great Plains. Boston: Ginn and Company, 1931.
Weiss, Ann E. Save the Mustangs! How a Federal Law is Passed. New York: Julian Messner, Division of Simon and Schuster, Inc., 1974.
Worcester, Don. The Spanish Mustang. El Paso: Texas Western Press, 1986.
Wyman, Walker D.and Harold E. Bryant (Illustrator). The Wild Horse of the West. Lincoln: University of Nebraska Press, 1963.
Goble, Paul. The Girl Who Loved Wild Horses. New York: Simon & Schuster Books for Young Readers, 1978.
Henckel, Mark and Michael H. Francis (Illustrator). Wild Horses: Wild Horse Magic for Kids (Animal Magic for Kids). Milwaukee, WI: Gareth Stevens Publishing, 1995.
Henry, Marguerite and Wesley Dennis (Illustrator). Horseshoe Library (3 Volume Boxed Set): Misty of Chincoteague; Stormy: Misty's Foal; Sea Star: Orphan of Chincoteague
Hope Ryden. The Wild Colt: The Life of a Young Mustang. New York: Cowards, 1972.
Isenbart, Hans-Heinrich and Thomas David (Photographer). 1986, Birth of a Foal. Minneapolis: Carolrhoda Nature Watch Book, 1986. (ages 7-10)
Viola, Herman J. After Columbus: The Horse's Return to America. Washington: Smithsonian Institution, 1992.