SharpDisasm:

SharpDisam is an x86 disassembler written in C# able to decode binary executable code for the x86 and x86-64 CPU architectures into disassembled instructions. The project is a C# port of the libudis86 disassembler C-library.
http://sharpdisasm.codeplex.com/

SharedMemory:

C# shared memory classes for sharing data between processes (Array, Buffer and Circular Buffer). This class library provides a set of C# classes that utilise the .NET 4 MemoryMappedFile class for fast low-level inter-process communication (IPC) – specifically for sharing data between processes.
http://sharedmemory.codeplex.com

EasyHook:

The reinvention of Windows API hooking – EasyHook starts where Microsoft Detours ends.
This project supports extending (hooking) unmanaged code (APIs) with pure managed ones, from within a fully managed environment like C# using Windows 2000 SP4 and later, including Windows XP x64, Windows Vista x64 and Windows Server 2008 x64. Also 32- and 64-bit kernel mode hooking is supported as well as an unmanaged user-mode API which allows you to hook targets without requiring a NET Framework on the customers PC.
http://easyhook.codeplex.com

Direct3DHook:

Direct3DHook – a starting point for hooking Direct3D 9/10/11 for image capturing fullscreen Direct3D content. This project uses EasyHook to inject into the target process.
https://github.com/spazzarama/Direct3DHook
http://spazzarama.com/2011/03/14/c-screen-capture-and-overlays-for-direct3d-9-10-and-11-using-api-hooks/

Afterglow:

A plugin framework to perform image capturing, colour extraction, post processing and colour output – primarily for use with lighting systems such as for ambient lighting. The project is inspired by Adalight and includes instructions for implementing an Arduino ambient lighting system.
http://afterglow.frozenpickle.com/

C#raft:

C#raft – an open source C# minecraft server. The goal of this project is to provide a rearchitected scalable minecraft server allowing large numbers of players.
http://www.c-raft.com/