While Wayne's comments seem to make some sense, the brightness of the ambient lighting in the viewing environment can also play a significant role in how images are perceived, whether the images are displayed on a monitor or in print. So, what would "typical" viewing conditions be like when accounting for ambient light?
Personally, the only standard reference for me for Web viewing is my iPad, since that is what I am most likely to use for showing my images to others on a computer screen. For that purpose, it is most likely that I would process the images a little darker than what I would use for printing, but it will sometimes depend upon the image.
As for the color balance of typical monitors, with reference to mobile anyway, it seems to me that the color balance of modern Apple mobile screens starts off rather cool and gets warmer with age and use. So what could the standard be there? I just stick with the best color balance I can get on a high quality editing monitor.