My favorite dog training/behavior sites:
Sue Ailsby's Training Levels - great resource for training dogs to be everything from good pets to conformation dogs to performance dogs to service dogs. I also enjoy her Training Levels email list.
www.dragonflyllama.com
Susan Garrett's website and blog. Good info on performance training.
www.clickerdogs.com
Silvia Trkman's website. REALLY cool website with lots of photos, videos and articles. Focused on agility and tricks but training info is useful for other stuff too. And the trick videos are really fun! Silvia is a top agility competitor who has won national and World Agility Championship and has a great relationship based approach to training.
http://silvia.trkman.net/
Suzanne Clothier's Flying Dog Press. Lots of good articles, although you now have to regsiter to view them.
http://flyingdogpress.com/
Clicker Solutions is a good collection of keepers from the email list of the same name. Offers information on everything from getting started to teaching behaviors to problem solving with clicker training plus training plans, horse clicker training, online training journals and FAQs (with some well known authors too).
http://www.clickersolutions.com/
And last but not least Shirly Chong's site with lots of training how tos including six lessons on training the most important behaviors, Mind Games-her version of NILIF, teaching retreive, ClickTrain Keepers and how to make your own recirculating bathing system at home (if you have never used one, you don't know how much easier your life could be ;) ).
http://www.shirleychong.com/
For books I enjoy:
Control Unleashed by Leslie McDevitt
Shaping Success by Susan Garrett
Steppin Up to Success Book One by Terri Arnold (competition obedience)
Choose to Heel by Dawn Jecs (competition obedience)
Tricks of the Trade by Pat Hatsings (show dog book mostly but with lots of good practical dog care advise too)
See Spot Live Longer by Steve Brown (about how diet affects the health and longevity of our dogs)
Planet Dog by ?? (just a really fun all things dog book)