http://www.geofflawrence.com/exposure_compensation.html

I actually do this a lot..try under exposing evening sun..especially sunsets..watch your colors become rich and  vivid..

Over exposing in less than idea conditions can save a lot of time in post production.

More on the same subject

http://www.photoxels.com/tutorial-exposure-compensation.html

 I'd disagree with underexposing sunsets  (but i'd agree with the qualifier that otherwise you have to work on it in post processing - yes you get the colours and all, but you are sacrificing other parts of the image).  You need all the dynamic range you can get to get the colours and detail in the darks (unless you are going for a silhouetted sunset - in which case underexpose to your heart's content).

The sunrise photo below was exposed to the right (and even on the camera it said it was blown).  But you can see that is not the case in the processed version (maybe one or two parts in the clouds, but not the white the camera screen told me i took), and i have kept detail in what would normally have been just a mass of black (the foreground trees for example).  The camera (even when shooting RAW) apparently already gives the RAW file a contrast boost, meaning that what you see on the screen is skewed towards being blown and darkened so you dont really know what you actually took and what detail is there in the high andlow ends until you get it on your computer and process it.

http://www.renderosity.com/mod/gallery/index.php?image_id=2044316&user_id=409068&np&np

How did i do it? Luminosity masks (very simple once you get the hang of them) Go read this tutorial from Tony Kuyper:

http://goodlight.us/writing/luminositymasks/luminositymasks-1.html

Interesting idea...There are times when I'll intentionally over  expose an image..The important thing is to understand it..so you can use it creatively

 Interesting !
I'd like to learn about everything in photography !
I love it ! 
5/5