Found this today, thought it was a good piece. Photographing indoor martial arts tournaments can be a real challenge, because flash is seldom a good idea during a competition, but the light is low and movement is fast (and gymnasium lights are often very non-white-balanced, which leads to ugly color casts). Photographing dance competitions and martial arts competitions have much in common, so you might like this:
http://photocritic.org/low-light-photography/
http://photocritic.org/low-light-photography/