ZweiDe is a 2d game development framework written in the .net environment.
It covers graphics, sound, user input and several other game-relevant programming areas and is inspired by the BlitzMax language style.
Features:
--> Simple structure / Easy to use
--> User input processing
--> Fast graphics (GLFW & OpenGL)
--> Sound supported by irrKlang
--> Detailed online manual (see website)
--> Several example projects
--> Project template for Visual C# Express 2005
--> Load and save most common graphic file formats (powered by DevIL)
--> Optional pixel-perfect textures
--> Vertex coloring
--> Render2Texture via FBOs
--> Optional Z-Buffer usage
--> Accum- and Stencil-Buffer access
--> Load Bitmap- and Freetype fonts
--> Very fast text display (also formatted text!)
--> Many helper classes such as LogFIle, Profiler, Vector2D, ...
ZweiDe is a commercial project; currently a ZweiDe full version license costs 10 € and can be purchased via Share*It.
You may take a look at the (though, not up-to-date) Demo version or the source demonstration program which is what I recommend to get an impression.
Edit: Due to an unexpected incompatibility between Mono and irrKlang I'll have to move "platform independency" from the feature list - sorry!