About 8 or ten years ago I started thinking about doing a graphics demo for the demo scene. I started to prepare a minimum skeleton that should compile to the smallest possible exe. Over the years I kept this Skeleton alive going from Windows XP to Windows 7 and from DirectX 8 to DirectX 10.
More than three years ago I put the source code up on Google Code here and kept updating it:

http://code.google.com/p/graphicsdemoskeleton/

Although the source code is rather short, I played around with many ideas over the years. I read articles by the demo scene about getting smaller exe’s just by using Visual Studio. After realizing that my exe got bigger with every new Visual Studio version, I switched to Pelles C; a free development environment with a compiler that follows the C99 standard:

http://www.smorgasbordet.com/pellesc/

My exe is now 838 bytes in size without violating Windows rules about releasing occupied resources. I tried to replace some of the code with assembly code, especially the entry points of the D3D functions and saved a few bytes at some point in time but removed it again because it was too inconvenient.
At some point (probably while it was running on DirectX 9) I implemented a small GPU particle system that didn’t add much to the size, which was pretty cool.
One of the interesting things I found out was that HLSL code was packing in some cases smaller than C code for the CPU. I found this remarkable and I thought it would be a cool idea to write a small CPU stub and then go from there in HLSL.
I know there will be times when I go back to this piece of code and wonder what else I can do with it and spend half an hour looking through it. It was certainly the project with some of the lowest priorities in the last ten years … maybe you can take the source and do something cool with it :-)

There is also a whole demo framework released by Inigo Quelez here

http://www.iquilezles.org/www/material/isystem1k4k/isystem1k4k.htm

Other useful links are:

http://yupferris.blogspot.com/

http://4klang.untergrund.net/