The SharpOS Project is a community effort to write an operating system in .NET, with a strong sense of security and managability.

Please note that the GPLv3 license includes the Classpath Linking Exception.

OpenRA is a Libre/Free Real Time Strategy game engine supporting early Westwood games like Command & Conquer and Command & Conquer: Red Alert.

TagLib# is a library for reading and writing tags in various formats for audio and video types. It provides generic support for robust tagging features and audio and visual properties, as well as format specific features.

Caliburn is a framework designed to aid in the development of WPF and Silverlight applications. It implements a variety of UI patterns that are geared towards solving problems encountered in real-world scenarios. Some patterns that are enabled by the framework include MVC, MVP, Presentation Model (MVVM), and Commands. Caliburn is based on several years of real-world development with WPF and aims to bring techniques developed in those projects to developers on both the WPF and Silverlight platforms....

Libgdiplus is the Mono library that provide a GDI+ comptible API on non-Windows operating systems. Our implementation uses Cairo (http://www.cairographics.org) to do most of the heavy lifting.

The Qpid Project provides an open and interoperable, multiple language implementations of the Advanced Messaged Queuing Protocol (AMQP) specification and related technologies including PGM, transaction management, queuing, distribution, security, management and heterogeneous multi-platform support for messaging....

Mono.XNA is a cross platform implementation of the XNA gaming framework. It runs on Windows, MacOS and Linux using OpenGL for 3D support.

ILSpy is the open-source .NET assembly browser and decompiler.,

ActiveWriter is basically a tool to model entities and relations between them. It consists of a modeller and a code generator. Entities are generated as C# or VB classes.

There are many tools to generate classes from diagrams, and ActiveWriter is not the best of them if it's only the class generation. What makes it useful is that, you can instruct it to decorate generated code with necessary ActiveRecord attributes. This way, you can instantly persist your entities to a database, retrieve them and walk through them using entity relations....

MediaPortal turns your HTPC into a very advanced media center, or Home Theater PC (HTPC):

- Listen to music and radio
- Play videos, movies and DVDs
- View pictures or create a slideshow
- Watch, schedule and record live TV - like a TiVo, but more, and for free! ...