polo 

SharpSerializer is an open source XML and binary serializer for .NET. With only one line of code it can serialize types like: multidimensional array, nested array, array-of-arrays, polymorphic object (where value is inherited from the property type), generic type, generic listing (i.e. dictionary,... More information

MCM (Message-Command-Message) is an open source framework for building modular, military simple .NET applications and state machine APIs of any size. Highly recommended is using it with Visual Studio Templates from http://www.mcm-framework.net

AppServices is an open source Service Container with IoC and Dependency Injection for .NET Full, Compact and Silverlight/WP7 (Windows Phone 7) Refer to http://appservices.codeplex.com for usage examples and more details.