From Arcane Corporation:
DatePal Pro, the Pocket Outlook Calendar Assistant, gives you the freedom to manage your Pocket PC calendar quickly and easily. With DatePal Pro you can: add and remove holidays; search for appointments, holidays, and events; remove old appointments; and enter your own holidays or special occasions. Once installed on your Pocket PC, DatePal Pro does not require resyncing. Holidays (and their descriptions) for over 35 countries and 3 religions (Christian, Jewish, and Muslim holidays) can be added and removed with just a few taps.