Most useful .NET utility classes

Question

Hi,

This post is for all .NET developers who often tries to reinvent the utility classes which already does by many programmers around the world.

I request everyone to please post your favourite utility classes(with code) here.

To start the show, Given below is the c# code for multithreaded singleton.

Multithreaded Singleton

using System;

public sealed class Singleton
{
   private static volatile Singleton instance;
   private static object syncRoot = new Object();

   private Singleton() {}

   public static Singleton Instance
   {
      get 
      {
         if (instance == null) 
         {
            lock (syncRoot) 
            {
               if (instance == null) 
                  instance = new Singleton();
            }
         }

         return instance;
      }
   }
}

Thanks, Mahesh