So: yoga and the martial arts. There are the obvious benefits, such as breath control, neuromuscular control, balance and strengthening of balance muscles, &c, &c. I just wanted to further my continuous furthering of the disparate arts by pointing some more specific examples:
-the frog-variation of the child's pose is the exact position one needs to be in for a side-mount, a pin common to Eastern grappling arts, which requires just that kind of flexibility and relaxation to be effective.
-when one does spinal twists in yoga, it is the same positioning for the twist necessary for most strikes and even throws; in that regard, the deep breathing done in the yoga twists amplifies the power of the martial arts techniques.
-yoga is one of the few ways i can think of to effectively strengthen the fine (in the small sense) stabilizing muscles throughout the body. For example, the eagle pose and side plank poses of yoga catch stabilizing muscles in the ankles and obliques that make one able to finely control their balance in very awkward positions.
-by controlling one's breath in odd positions (twisted and folded, or upsidedown, or arched), one gains the ability to relax in many odd positions, and (especially in the case of any kind of jujitsu, for example), relaxation and control in tremendously strange positions is very helpful.

In that line of thought, Yoga Journal is very much worth the money it costs. It's articles consist of how-to, advice, world culture, meditation, media reviews, and various columns. Its column on psychology has continuously been interesting and immediately useful in my opinion. Also, their website is a huge resource concerning poses and articles on myriad health related topics.

Finally, an interesting idea I came across in one of those articles: that an emotion is something in between a mental and a physical experience.