I'm just new in the photo world but I've been reading around magazines and books to learn much as I can on the subject and I found an article about this color calibration mater.
As there are many displays around a picture (scanner, camera, screen, browser, print settings etc ...), there are equally numbers of chances to "loose" the color at a specific moment or another.
I just purchased a D7000 and it seems that cameras + screens need to be adjusted. It still seems to be an "underground" subject but important though if you want the colors being unchanged from what you shoot to what you post on a forum or print on paper.
The camera :
Except maybe for professional devices that are more precisely adjusted from the factory (maybe that your D800 is concerned by this higher attention), a camera doesn't seem to be properly color-set.
Thus you can buy color-chart kits that help you create a right color profile for you camera. You also have on-line companies that send you these charts, ask you to take a photo in specific conditions and send them back the result. They then send you a profile to be included on your computer etc ...
The screen :
You maybe already heard about the "spiders", little cameras that you maintain on your screen while it analyzes it and create the right color profile for your screen. I found a French site who already provides a dowload of your screen .ICC profile to include on your hard drive.
The internet browser :
Adobe RVB color panel is wider than sRVB panel. But, if you take pictures to post them on the internet, then you should convert them in sRVB if your camera was set on Adobe RVB.
Of course, most of the people who surf on the net, don't calibrate there browser. Troubles come whether an .ICC profile is attached to the picture or not and when the browser is not properly configured. Significant mistakes in color choices can arise. That's why it is better to convert them in sRVB as most of the browser will react correctly. It's better to provide a picture that don't have these colors flaws instead of having only 5% of the screens showing the pics correctly.
I'm maybe not that clear but you'll find your way for sure :p
Is all this calibrating thing necessary ? I don't know but I tried to do it myself as it seems that some mistakes can be significant depending on settings.
I'm sure you can find articles in english about this. If you need some names of displays don't hesitate to ask, I'll take a look at my readings
Cheers,
Mark