Here's a great link you might want to bookmark. Its a pretty good reference of GOF (Gang of Four) patterns and has sample C# code

Requirements Exam 70–315: Developing and Implementing Web Applications with Microsoft Visual C#™ .NET and Microsoft Visual Studio .NET Exam 70–316: Developing and Implementing Windows-based Applications with Microsoft Visual C# .NET and Microsoft Visual Studio .NET Exam 70–320: Developing XML Web Services and Server Components with Microsoft Visual C# and the Microsoft .NET Framework Exam 70–300: Analyzing Requirements and Defining Microsoft .NET Solution Architectures...