Easy Datetime.Min/Max implementation.

gistfile1.cs

internal static class DateTimeUtil
{
    public static DateTime Min(params DateTime[] values)
    {
        if (values == null)
            throw new ArgumentNullException("values");

        var comparer = new DateTimeComparer();
        Array.Sort<DateTime>(values, comparer);
        return values[0];
    }

    public static DateTime Max(params DateTime[] values)
    {
        if (values == null)
            throw new ArgumentNullException("values");

        var comparer = new DateTimeComparer();
        Array.Sort<DateTime>(values, comparer);
        return values[values.Length - 1];
    }
}

internal class DateTimeComparer : IComparer<DateTime>
{
    int IComparer<DateTime>.Compare(DateTime x, DateTime y)
    {
        var v1 = x.ToUniversalTime();
        var v2 = y.ToUniversalTime();
        return v1.CompareTo(v2);
    }
}