Just some links to colour resources and tools that are available online:

• 4096 Color Wheel: Helps you to select colour variations that are web-smart.
• Color Blender: Download your colour scheme as a Photoshop file (.act), Illustrator files (.eps) or email it. Also match your colour to a Pantone colour.
• ColorJack
• Color in Motion
• Color Lovers: Colour palettes and trends by members.
• Color Palette Generator
• Colors on the Web: Covers colour theory, physics, psychology and also has a couple of tools: Colour Wizard and Color Wheel.
• Color Schemer and its gallery
• Color Scheme Chooser
• Color Tool: The colours you select affect the page so you can immediately see your colour combinations in action.
• Color Toy
• ColorWhore
• ColorZilla A FireFox extension
• Colr.org: Lets you get a colour scheme from an image as well.
• CSS Colour Chart
• Easy RGB Includes tools such as colour matching, colour harmonies, colour calculator, search for tints, colour calibration and software.
• Eric Meyer’s Color Blender
• Kuler: Colour schemes by members. You will need to login to download colour schemes.
• Pic2Color: Extract colour schemes from pictures.
• Web 2.0 Colour Palette
• Well Styled Color Schemer

Colour Accessibility Tools:

• Color Blind Simulator: Upload photos to simulate two types of colour blindness.
• Color Blind Web Page Filter: Enter your URL and run the filter.
• Jonathan Snook’s Colour Contrast Check
• GrayBit GrayBit is an online accessibility testing tool designed to visually convert a full-color web page into a grayscale rendition for the purpose of visually testing the page’s perceived contrast.
• Juicy Studio’s Colour Contrast Analyser
• Vischeck: Lets you run images and web pages through the simulator to test for three types of colour blindness.

Web Colours Further Reading:

• 24 Ways: Cheating Color
• 24 Ways: Photographic Palettes
• Bite Size Standards: CSS values for colors
• Digital Web: Color: An Investigation
• Digital Web: Color Theory for the Color-Blind
• Mark Boulton: 5 Simple Steps to Designing with Colour
• Mezzoblue: CMYK (for those of do RGB)
• Mezzoblue: Color Matching
• Veerle: Choosing Color Combinations
• Web Exhibits: Causes of Color
• Web Exhibits: Color Vision and Art
• Web Page Design for Designers: Colour Palettes

What have I missed?