While in designing a website you should not rely on color alone, it does help to know what the colors you choose are saying. Why does Google use 4 colors in their logo while Yahoo only uses red? Why did JetBlue choose this color as opposed to JetGreen or JetRed?
Do you know the meaning of colors? For example while blue is a male color portraying peace and sadness, green can portray newness. Color Psychology shows us what colors brings out what moods, emotions, and appetites. There are even tests that can analyze you based on color preferences. There is the belief that different cultures have completely different interpretations of color and no universal psychological reaction to a specific color exists. For example, death is symbolized by black in most Western cultures and by white in many Eastern cultures.
Various display devices also handle colors differently. CRT, LCD and a Phone screens, PCs and Macs, all have unique color rendering characteristics. To be complete also correct for color blindness. Sim Daltonism is a small yet powerful free OSX app to test your website for color blindness. It comes with 8 different filters to simulate everything ranging from partial to complete color blindness.