200 -- outdoors, sun shine, sunny day
400 -- outdoors/indoors, a good amount of available light
800 -- indoors or darker lit areas
1600 -- dark gymnasiums, indoor sporting events, some births or other darker indoor activities
3200 -- this is the speed that i use when shooting births. very limited available light.
a few other things to keep in mind when adjusting your iso... higher iso's increase the grain in an image. also, if you're struggling to get the right exposure with your shutter and aperture and you need your shutter to be faster than the amount of available light will allow--change your iso! increasing the sensitivity of the sensor will provide you more flexibility with your exposure and shutter!!