Someone in the Barefoot vs. Shoes forum asked about Navicular and keeping a horse barefoot. This is an excellent article explaining not only how Navicular problems can be fixed with proper barefoot trimming and a knowledge of how proper balance, but also the benefits of keeping a horse barefoot and preventing these sorts of problems.
I really liked how the article discussed the purpose of the different frog structures, where lameness can come from, the various beliefs about trimming the frog, and provided LOTS of pictures to illustrate. It also mentioned how "pretty" isn't always "best".
This is also an excellent article for those that believe that a barefoot trimmer is not "specialized" or knowledgable enough since they may not do shoes. Notice how it advocates how any professional - barefoot or otherwise - should do many cadaver dissections in order to truly understand the foot. This does not sound like the type a training a non-specialized or unknowledgable person would undertake. There are a lot of "barefoot" trimmers out there that really don't know what they're doing and believe that barefoot trim = pasture trim, but that is simply not the case.
Now, I still believe in hoof protection, but prefer to use boots (where possible) simply because, as this describes, proper barefoot trimming allows the hoof to grow and be maintained in a healthy and beneficial way. Unless a horse is one of the few that truly needs shoes (and they are much fewer and farther between than people think!), I have a hard time believing that shoes are better or even as good as barefoot for horses. It even talks about how the lack of frog pressure causes other leg problems - which are the most common injuries in endurance so this is a critical point to me.
If you truly want to understand why there are those of us that adamantly swear by barefoot trimming, or simply just know a little more about the importance and functions of the various parts of your horse's hooves, I urge you to read this article through to the end. I was tempted to stop reading after the first few paragraphs, but I'm so glad I didn't. To me, everything the author says makes perfect sense, and, toward the end, it really started to click WHY I felt so strongly about barefoot trimming beyond that it was simply "healthier". Prevention and Relief of Navicul