Holidays

From version 1.1, there's also an extension avaible to list all year Holidays.
IDictionary<DateTime, Holiday> AllYearHolidays()
Thru this extension on DateTime, it's possible to get all holidays for a given culture and his ocurrences on its year, like in the next example:

[Test]
public void get_this_year_holidays_in_portugal() {
    var portugalDateTimeCultureInfo = new DateTimeCultureInfo("pt-PT");
    var today = DateTime.Today;
    var holidays = today.AllYearHolidays();

    Assert.IsTrue(holidays.Count == 13);

    foreach (DateTime holidayDate in holidays.Keys) {
        var holiday = holidays[holidayDate];
        Assert.IsTrue(holidayDate.IsWorkingDay(portugalDateTimeCultureInfo) == false, "holiday {0} shouln't be working day in Portugal", holiday.Name);
    }
}

Check out the project ReadMe for a list of supported cultures

If your culture is not specified here, feel free to fork this project and contribute it. I'll add some cultures from time to time.