Summary of the Useful Websites

Free barrel racing tips -
Obviously it's about barrel racing. They have drills, exercises, tips, solving problems, and a few other things. You can subscribe to get tips by email.
The Horse Rider Blog -
This site has general stuff about horses and general tips. I like this one more for it's area in jumping training. But it has some great stuff on other topics too.
Horse Trix -
This one is actually a YouTube channel by Heidi Herriott. She shows you how to do some simple tricks including the bow and laying down. She has a website too.
Balanced Rider -
This is a sight on riding and being balanced. It includes the parts of the body used in riding, position, exercises for a better riding position, and a blog which has some really helpful things in it. I encourage you to go look at it. It could help anyone. It'll help you to understand riding and communicating with your horse better.
Keith Hosman
horsemanship101 -
Keith Hosman is a certified Josh Lyons trainer. He has a lot of general training. Training under saddle, ground training, manners, behavior, and that sort of thing. The articles on his website do require you to pay around a dollar for the rest of the article. But if you sign up you can get some good training tips through email that don't require you to pay anything. He has guest authors and videos that might be helpful.
Larry Trocha Training -
Larry Trocha specializes in cutting horses. I encourage you to subscribe to his website. He has some really great stuff. I've got emails from him on teaching rollbacks, spins, stops, fixing bad behavior, stallion advice, cutting, proper equipment use, and the like. You can ask him questions too. He doesn't guarantee that it will get answered though because he has many, many people asking questions. I'll make a post on him and get you some of the training emails I've gotten from him that I think are usefull. (Click Here) I like him because he's not afraid to put his neck out. He has some really good insight.
Haynet
This website isn't a certain discipline. It's actually a place for blogging, chatting, asking and answering questions, and reading other people's blogs. You can find a whole barrage of information. From general horse life to horse training. From horse breed to eventing. You don't even have to sign up. Sign up if you want to blog on that website.