EventAggregator.cs

namespace OMR.Core.Helpers
{
	using System;
	using System.Collections;
	using System.Collections.Generic;

	public class EventAggregator
	{
		public IDictionary<Type, IList> Subscribers;

		public EventAggregator ()
		{
			Subscribers = new Dictionary<Type, IList> ();	
		}

		public void Publish<T> (T instance)
		{
			IList actions;
			Subscribers.TryGetValue (typeof(T), out actions);

			if (actions != null) {
				foreach (Action<T> item in actions) {
					item (instance);
				}
			}
		}

		public void Subscribe<T> (Action<T> action)
		{
			if (Subscribers.ContainsKey (typeof(T))) {
				Subscribers [typeof(T)].Add (action);
			} else {
				Subscribers.Add (typeof(T), new List<Action<T>> () { action });
			}
		}

		public void UnSubscribe<T> (Action<T> action)
		{
			IList actions;
			Subscribers.TryGetValue (typeof(T), out actions);

			if (actions != null) {
				actions.Remove (action);
			}

		}

	}

}

Program.cs

using System;
using OMR.Core.Helpers;

namespace event_aggregator_sample
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			var ea = new EventAggregator();
			
			ea.Subscribe<int>(onEventRaised);

			ea.Publish<int>(1);

			ea.UnSubscribe<int>(onEventRaised);

			ea.Publish<int>(1);

			Console.ReadKey();

		}

		public static void onEventRaised(int i)
		{
			Console.WriteLine("Event raised with value of " + i);
		}

	}

}