.NET news » Graphics 
All-in-one printing utility for user controls
Vista Style Progress Bar in C#
Transparent drop shadow in C# (GDI+)
Transparent drop shadow in C# (GDI+ & Windows Forms)
An Alpha Composited Windows Form
Windows has long had the ability to specify a region or transparency key allowing you to define an arbitrary Window border. This is often used with a background image to define an image outline as a Window frame. However, this border is composited with the desktop as a one bit mask giving you a pixelated boundary. It is especially unattractive with curvilinear borders which really need antialiasing and per pixel compositing. Aside from the unsightliness, it's not easy to define the region and/or transparency key to achieve a complex image based Window frame.
This is a Windows Forms control that works with Win32 APIs and without WPF. The control allows you to layout a 32 bit image with an alpha channel in the Forms designer and arrange additional controls within user specified areas of the image. At runtime, the control will generate a per pixel alpha composited Form with the desktop. The Form's Region property defines areas of the Form to host other controls, and it's calculated on the fly from the image's alpha channel. This control also supports runtime changing of the image. Before we discuss some of the code specifics, let's run through how you use it.
How to capture a Window as an Image and save it
GUI Library for Managed DirectX Applications
A thermometer control
Hue Saturation Lightness Filter
Manipulating colors in .net - Part 1
The fact is, in .net, there are only two color formats that can be used : the RGB color model and the HSB color model. Those two are encapsulated in the Color structure of the System.Drawing namespace. It is largely sufficient for simple uses, like changing the background color of a component, but insufficient if we want to develop graphic tools (or something which implies conversion between color formats).
I've started looking for other formats, like CMYK, when I was learning how to add cool design-time support to my custom controls.

