To design a colour scheme for a web page, for example, is not the easiest thing in the world. One of our homeworks includes to do exactly that, based on a wireframe model of the navigation of the page. How do you create a harmonic and balanced colour scheme without being too dull and highlighting the areas of interest? Luckily, there are many webpages to help you with that. Especially Skout has several good links in the colour section to help one through. (I played a lot with them last week.) The approach for design starting from navigation, colours, etc. suits me perfectly, since I'm rather organized. We have to code a homepage in few weeks, I have to start thinking the colours for that soon, too.
Here are some random parts from Coloria.net. It's only in Finnish, but astonishing with the amount of information about colours...
Red: On top of the typical ones, red is also "the colour of imagination which evokes feelings of celebration".
Blue: There are no known mentions about blue from the time of ancient Greece. Maybe the people didn't see it as we do?
Green: The colour of persistence, pride, even youth.
Yellow: Black text on yellow background is the best combination for printed paper. :o
Black: "Put on your thinking cap." The saying comes from the habit where the judge places a black cap on his head before announcing a capital punishment.
White: There was a white stone in the temple of the Oracle of Delfoi. The stone was said to be the center of the Earth.