Color Psychology
Infoplease page about Color Psychology
It's important to note that colors are differently associated with different cultures. For example, here's this culture comparison about color in China and the United States:
Group-Mail Colors in Culture Article
There are strange and surprising differences - for example, while white in western culture is associated with weddings and purity, in China it is assigned to funerals and mourning. Do not assume that EVERYONE who views your website will be affected the same by color and color associations.