A simple in-process semaphore using C#
- Creating a semaphore to limit a given number of threads accessing a resource in a process.
- http://www.codeproject.com/csharp/inprocsemaphore.asp

ExoEngine
- A C# OpenGL 3D game engine. Written to show that C# can in fact be used for real-time 3D game engine development. [Open source]
- http://www.exocortex.org/3dengine/

Open Source Software in C# (C-Sharp)
- Directory of open source software focused in C#.
- http://csharp-source.net/

C# Code Samples
- Small example programs in c#, each showing a concept: plugin, parser, morpher.
- http://spiet.ath.cx/c-sharp/

C# Code Demos
- Demos of working C# solutions, featuring XML, reflection, SQL and WinForms.
- http://www.meissnersd.com/csharp.htm

The Code Project
- Formed to provide developers with a place to meet and exchange ideas. Intents to provide the resources needed to help developers in their day to day programming, as well as helping them keep up to date with the latest technologies.
- http://www.codeproject.com/csharp/