ColorPicker
ColorPicker for WPF and Silverlight is a color input editor that provides a rich, interactive color selection interface. Users can select colors from professionally designed palettes or custom colors that you have chosen.
You can choose to include a basic color palette with preselected and standard colors, an advanced palette that users can use to completely customize their color selection, or both! ColorPicker for WPF and Silverlight even includes transparency, hexadecimal color, and RGB and HLS color model support to provide a rich visual color input interface.
See Also
Quick Start: ColorPicker for WPF