Dr. P's Dog TrainingIt doesn't get any better than this. Dr. Mark Plonsky has put together a staggering resource of quality dog training and behavior articles. Brilliant website covering all aspects of dog care, training and health issues. You could literally spend days exploring this site.
Karen Pryor Clicker TrainingFor anyone interested in Clicker Dog Training this is the website for you - there is even some free sample video of the clicker training process in action.
K9 EventsThis is a huge resource of dog training tips, articles and advice. It can be a bit tricky to navigate your way around this website but it really is worth the trouble. Whatever stage you are at with your puppy or older dog you will find relevant, quality information within this great Australian dog training website.
Dogpatch - The Dog Obedience and Training PageAnother fantastic collection of basic dog training information, behavior problem articles and obedience training tips.
PetPlace - Dog Training TipsAnother great website for us dog lovers to explore. This site has hundreds of high quality articles covering such topics as - how to choose a puppy, how to properly feed your dog, solving problem behavior in dogs and how to train your dog.
The Humane Society of The United StatesLots of articles mainly discussing the health and proper care of your dog. You'll also find some free dog training videos presented by animal behaviorist Tamar Gellar.