ISO Safety Shift
Roger Longenbach recently wrote to me and said "I love the ISO safety shift. I haven’t turned it off. With the low noise of the MkIII who needs to."
I did some looking into this feature (C.Fn 1-8) and it really seems like a cool feature.
I'm going to try this setting this weekend when I go out and do some sports shooting. I'll set my camera to Tv mode, set the shutter speed to about 1/640th or 1/1000th depending on the lighting. With my slow-ass lens (100-400mm f/4.5-5.6L IS) if wide open shooting is not enough, the camera will automatically adjust the ISO for me. Sounds cool.