Since the release of this nice feature for the .NET Framework, many of us are using extension methods to simplify our code. And according to the DRY principle it’s best to not re-invent the wheel. So, you can search for already “invented” extension methods in the site http://www.extensionmethod.net/
ExtensionMethod.NET is a database of C# 3.0 and Visual Basic 2008 extension methods. It contains many user-rated extension methods that will expand your code library immediately.
Extension methods add functionality to existing classes and allow you to expand the .NET framework. This way your favorite functions integrate seamlessly into the framework. For more information about extension methods visit the C# 3.0 and Visual Basic 2008 MSDN Library pages.