Free APB:R All Points Bulletin server emulator. Write on C#,

Qt4 bindings for Mono/.NET
Based on the SMOKE library,

The Silverlight Toolkit is an open source project, a place where the Silverlight Team at Microsoft shares new components and functionality for designers, developers, and the community to provide an efficient way to help shape product development. Toolkit releases includes full open source code, samples, documentation, and design-time support for controls focusing on both Silverlight 4 as well as the Windows Phone....

Lokad CQRS helps to build scalable cloud applications for Windows Azure.

It provides time-proven guidance and .NET Application Blocks to help architects and developers deliver solutions ranging from high-traffic web sites to feature-rich enterprise solutions....

MsSqlSpatial - Spatial Extensions for SQL Server 2005.

This project conforms to OGC Simple Features Specification for SQL Revision 1.1 and provides many useful features to power GIS applications.

Witty is a Twitter client for Windows Vista and XP that is powered by the Windows Presentation Foundation (WPF).

Witty includes the following functionalities:

• View recent Twitter statuses from the people you follow (auto-refreshing)
• View recent replies to you...

IronRuby is an Open Source implementation of the Ruby programming language. It is built using the Dynamic Language Runtime, which makes it easier to build high-quality dynamic language implementations on top of Microsoft's .NET Framework.

Nemerle is a high-level statically-typed programming language for the .NET platform. It offers functional, object-oriented and imperative features. It has a simple C#-like syntax and a powerful meta-programming system.

Features that come from the functional land are variants, pattern matching, type inference and parameter polymorphism (aka generics)....

Ketarin is a small application which automatically updates setup packages. As opposed to other tools, Ketarin is not meant to keep your system up-to-date, but rather to maintain a compilation of all important setup packages which can then be burned to disc or put on a USB stick....

shaim is an open-source multi-protocol instant messaging client written in C#.,