Derby Archive - a nice collection of photographs from Kinetic Corp., the official photographer and archivist of the Kentucky Derby. You can also purchase photos from them.
Life Magazine Classic Derby Photos - a collection of 9 photos from the Kentucky Derby that appeared in Life Magazine in the 1940's to 1960's
Preakness
Preakness History - list of all past winners plus historic info about the race from Pimlico
Past Winners - with breeding, connections, time, odds, etc.
Belmont Stakes
Belmont History - all past runners, triva, and other history from NYRA
Past Winners - with breeding, connections, time, odds, etc.
Triple Crown Winners - with jockey, trainer, and owner plus links to info about each
Failed Triple Crown Attempts - details about all the horses who have won the first two legs of the Triple Crown only to fail in the Belmont.
