In Microsoft Outlook you can automatically add your country’s national holidays.

In the “Tools” menu, select “Options”

In the “Preferences” tab on the Options-screen there is a “Calendar”-section. Click on “Calendar Options”

In the “Calendar options”-section of the Calendar Options (I swear, I’m not making this up) press the “Add Holidays…”-button.

Now a list appears with all the countries for which national holidays are known in Outlook. Select the countries of which you want the holiday information imported in Outlook and click “OK”.

Office 2010 now availble on Technet and MSDN