This is sick. Someone has to get these guys to turn this Color Mixer Light into a product. Go check out their demo.
The lamp looks like LEDs attached to metal cylinder inside a globe of plastic cups. Their hardware remote has 3 analog knobs to control the mix of Red Green Blue light, with level indicators for each color on a small LCD. They are also able to control RGB values from an iPhone app--looks like an SSH or terminal window with Unix commands to set values. I want this in my house.
Yet another beautiful application using the flickr API. colrpickr generates a set of photos from flickr based on color value selected from a color chart.
Adam's color forecasts for the year.
An excellent browser-based color scheme generator.
A directory of nice colors.
Painter's Picker is an extension to the color picker panel in Mac OS X. It adds the ability to choose related colors, such as complementary colors, analogous colors, etc. directly within the color picker. It also adds more precise controls for choosing saturation, hue angle, and brightness, and provides the ability to choose colors in the CMYK color space while using the popular HSB-style controls. Painter's Picker has been designed to be the simplest way to perform complex color selection within nearly any application in Mac OS X.
In this article in Boxes and Arrows, Luke Luke Wroblewski discusses the use of color in user interface design to distinguish a site, and to guide, engage and inspire users.