WPF ColorDialog Extended control and dialog window
also possible for Silverlight, WinRT, Win8, WP8
WPF ColorDialog control and dialog windows. You can embedd only control into you application, or use "ready to use" ColorDialog windows - small and big.
(a better description be later)
A library with advanced control and two dialog windows for .Net 4.0 and .Net 4.5.
Currently develop for WPF, but seems like possible to port for other platforms via recompilation...
Codeplex project created and first beta release uploaded