Color psychology on Wikipedia
Wikipedia is a great online resource for many things. One of those is color symbolism and it goes on with an overview of each color and links to a fully detailed article on each color.

Exerpt:

White

White is the color that represents purity, neutrality, sterility and youth. White is often associated with cleanliness or sterility. White is also associated with neutrality and peace — hence a white flag for surrender or parley. For the same reason it is a neutral color that will continue to be the preferred backdrop on websites and the “color” behind the color. In Western tradition the bride wears white, a custom dating back to Ancient Greece. There, the temple that was dedicated to the goddess Athene was made of white marble. It led to the linking of the color to virginity.

White is known for symbolizing light, reverence, purity, truth, snow, peace, innocence, cleanliness, simplicity, security, humility, sterility, winter, coldness, surrender, fearfulness, unimaginative, air, death (in Eastern cultures), life, marriage (in Western cultures), hope, bland, empty (interior) and January (winter).

Color Psychology on About.com
About.com, another good resource for color meaning. It also has a lot of interesting information on color and the science of it and also goes into the meaning of each color.