Two related articles from Photodoto today:

The first Managing dynamic range through better metering explains why photos that meter correctly can appear washed out or muddy, and what you can do about it, with some reference to the on-camera histogram that many modern digital cameras offer.

The second, There is no such thing as a "perfect" histogram compares the shape of your classic 'good shot' histogram to those that you get when you've taken a photo with deliberate effect, which may mean that your histogram is completely 'wrong', while you have a great shot.