Huey Color Picker - What programmer-designers have been waiting for: a no-shit freeware HTML colour generator that converts RGB values to Hex and from Hex back to RGB. Or pick directly from any part of the screen with the Colour Pipette feature.

ColorPicker 3.0 - This color picker will help you fine tune the hex color codes for your web page. First choose whether you wish to play with the Background Color, Text Color, Link Color, Visited Link Color, Active Link Color or Hover Color and check the appropriate round radio button.

Color Schemer v3 - Color Schemer v3 is a quick and easy-to-use tool that will help you to create matching color schemes at the click of a button! Color Schemer v3 features many built-in tools including multiple color-matching modes to find the best matching colors, the ability to view harmonies right on the color wheel, and a mini QuickPreview to test colors in a web page setting!

Choosing Coordinating Colors - The following section will help you choose coordinating colors. This is a helpful tool for website building,

Online Color Schemer v2 - Enter an RGB or HEX value, or click on the Color Palette.

Visibone - Want a hard copy reference card? Here you go!

WebMonkey — Color Codes Reference - The color table is here!

Worqx - A comprehensive website with in-depth information on color theory. Very informative.