Danes Online: Puppies, breeders, newsletter, photos, discussion.
Danes Online (DOL) Discussion Forum: A comprehensive resource for discussion and advice on everything Great Dane (selecting a puppy, training, ear cropping, breeding, feeding, health, photos, meetups, special announcements, etc.). Membership is free.
Ginnie's Great Dane Links Directory: Ton's of useful (and fun) Great Dane links and resources.
Danes-R-Us: Fun Great Dane themed shopping.
AKC Meet the Breeds - Great Dane: Breed Standard
Montrose Harbor Dog Beach - A huge fenced beach in Chicago on Lake Michigan dedicated to off-leash dog play.