Shuffle IEnumerable extension method using Fisher–Yates shuffle algorithm (http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)

ShuffleIEnumerable.cs

public static class EnumerableEx
    {
        public static IEnumerable<T> Shuffle<T>(this IEnumerable<T> enumerable)
        {
            var array = enumerable.ToArray();

            var random = new Random(DateTime.Now.Millisecond);

            for (int i = array.Length - 1; i >= 1; i--)
            {
                var j = random.Next(0, i + 1);

                Swap(array, i, j);
            }

            return array;
        }

        private static void Swap<T>(T[] array, int i, int j)
        {
            var aux = array[i];
            array[i] = array[j];
            array[j] = aux;
        }
    }