Online

• Wolfram Alpha
• Wikipedia Colour

Download

• RGB Hex Colour Chart
• Web Designer's Color Card/Font Card
• The 216-Color Webmaster's Palette Poster
• Web Designer's Color Chart
• Web Color KiloChart
• Web Designer's Color Hexagon Mouse Pad
• CMYK Reference
• Web Safe Colors
• Colors from the Inside Back Cover
• Reference: Color Codes