Okay, first off: I'm not about to get into a who's better Mac-Or-PC tiff with Anybody (I've had both and used both). Frankly I'd rather argue religion, politics, AND sex before getting into that. There's no rights or wrongs here, just differences. So if you care to comment, leave your platform outside the box.
While researching separate issues for the Photoshop Tips blog, though, I happened to run across an answer for a question I had not yet fully formulated. Which is: Why is there such a range of contrast among Internet images? While each blog tends to have a consistent range of picture quality, some blogs images may appear to some of us as overly light or overly dark (and, like Goldilocks, some are 'just right').
Apparently we can thank something called GAMMA VALUES. From the Photoshop 'Help' files: "The gamma value of a computer monitor affects how light or dark an image looks in a web browser. Because Windows systems use a gamma of 2.2, images look darker on Windows than on Mac OS systems, which are normally set to a gamma of 1.8."
Sample of what an image might look like created on a PC (but viewed on a Mac)...

...vs. how it might appear created on a Mac (but viewed on a PC).

(image: Golden Wings Deaux, oil, 36" x 36")
Depending on whether you are viewing form a Mac or a PC, one of these images will likely appear 'more correct' than another.
For an easy tutorial on how to 'average out' your photos for the masses, see today's Photoshop Tip on Adjusting Gamma.
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