Dog Breeds
These are the authority sites on dog breeds around the world:
American Kennel Club - The comprehensive list of approved breeds in the US. Great for formal definitions and characteristics of breeds. Includes national breed clubs.
DogBreedInfo - Also good on breed content, with a little more warmth. Has a "Choosing a breed" quiz that came up with some lesser known breeds for me.
Australian National Kennel Club - As per the AKC. At least this site includes Australian breeds like the Kelpie.