[.NET - CSharp] Software Design Patterns in C#
The Data and Object Factory has a nice presentation of software design patterns including downloadable source code in C#. You will probably find a visit there worthwhile. For each pattern, the authors provide a structural example and a "real world" example. The code is generally clear, concise, and instructive. For example, take a look at the very simple but cool "real world" example where the authors show how to use Singleton to implement a rudimentary LoadBalancer object. Nice!