DirectX Samples in Boo
These are examples that use the Managed DirectX API for .NET. They require the DirectX SDK from Microsoft.
And of course these run on Windows only. For a cross-platform alternative for 3D graphics, see OpenGL 3D samples.
This is the code from tutorial 5 included with the DirectX SDK, converted to boo (mostly converted automatically by the boo sharpdevelop addin).