This is a sample application that is built by one of my colleuges -- Serena Yeoh, to illustrate how to develop .NET applications using the Layered Architecture design pattern. It is not a full-blown application but a simple example to demonstrate the factoring of responsibilities and separation of concerns into multiple layers in an enterprise application.

You can download the sample application from codeplex:http://www.codeplex.com/LayerSample 

For reference on Application Architecture for .NET: Designing Applications and Services, please visit: http://msdn2.microsoft.com/en-us/library/ms954595.aspx