I'm currently researching hooves and I found a couple of great articles and diagrams I thought I would share!
Excellent diagram: Barefoot hoof diagrams - Detailed barefoot hoof diagrams showing the structures of the hoof
Informative introduction to hooves: http://www.heikebean.com/hoofintro.pdf
Incredibly in-depth article with tons of pictures: WHAT IS A HEALTHY HOOF AND WHAT DOES IT LOOK LIKE
If I find more I'll add them to this thread.