
Here is a program that I think very highly of and it's
HoliDates " HoliDates is a holiday application that not only adds holidays to your Palm Treo, Centro or PDA, but allows you to see upcoming, past and distant future holidays all in one place. Even if you already have some holidays within your Calendar, this feature is worth the price alone. No more having to go through your Calendar one day at a time to see what's coming up next month.
You'll want to add the holidays into Calendar as well. Choose the categories of holidays to add to Calendar. Click Install. They're added. Change your mind, click Remove and out of Calendar they come."