Microsoft Office like Color Dialog
BCGControlBar Pro (MFC)
BCGControlBar for .NET
This dialog is actually a property sheet with two pages. The first page allows to make a selection from one of the standard colors (from the system palette) using a list of colors in hexagon form, the second page displays a control that allows to select a custom color, using a luminance bar and hex display.
The user selects a particular color, which is then reported back to the application.
CBCGPColorDialog dlg (m_Color /* Initial color */);
if (dlg.DoModal () == IDOK)
m_Color = dlg.GetColor ();