RainbowPicker

RainbowPicker is a free and small utility for Mac OS X developers.
Rainbowpicker's small dialog interface resembles common color picker applications.

A small square spectrum of colors sits next to an array of predefined colors.
Hue, Saturation, and Brightness levels are displayed next to Red, Green, and Blue values, but the only number you can pull automatically from the application is the hex value.