Most web browsers (and some programs) are not colour profile aware and therefore in those circumstances you will be veiwing them in your monitors color space. When the srgb colour space was brought out ten years ago it matched the display of most low end computer monitors and hence the advise to use srgb for the web. The truth is that now most decent monitors can display a larger color gamut than srgb, so now srgb does not match your monitors color gamut now and hence the slight difference you are seeing on the web.
By the way using your montor profile as a color space does not mean others will see your images as you do because no two monitors are the same
