To start with, here are a few of my essentials:
http://www.ponyclub.org/ (or if you’re across the Pond: http://www.pcuk.org/)
This is the website for the Pony Club. I think this organization is one of the best I’ve ever seen! The teaching and competitions cover both riding and barn management, so participants learn about all aspects of horses. Pony Club emphases safety, leadership and versatility.
This link takes you to the homepage for the ‘Equus’ magazine. ‘Equus’ is a great source of horsey knowledge, from vet care to riding tips.
I’m not endorsing any particular brand (they don’t pay me anything) but I have always loved everything I’ve gotten from Ariat, particularly their boots!! They just seem to me to be good quality, long-lasting, and comfy. Plus, they’ve got some pretty spiffy non-riding shoes…
Let me know of any great resources you come across!