http://msdn.microsoft.com/stocktrader.
The StockTrader application is an end-to-end sample illustrating Windows Communication Foundation and building high-performance WCF applications. It includes both an ASP.NET front-end, as well as a Windows Presentation Foundation (WPF) smart client front-end. The sample also includes the Configuration Service, a set of shared libraries that can be used with any custom .NET application, ASP.NET application or WCF service host to provide load balancing, failover and centralized configuration management for WCF-based applications.