It's frustrating to make an appointment on your handheld only to get back to the office and realize that Monday is a legal holiday. But, if you're using Microsoft Outlook on your computer, then you can easily install national holidays for any of a number of countries, as well as religious holidays, on your mobile calendar. Those will then transfer to your handheld when you sync.

1. Open you calendar in Outlook
2. Select Tools --> Options, and click on Calendar Options.
3. Click the Add Holidays button.
4. Select the countries or religions (Christian, Islamic, or Jewish) whose
holidays you want to add and click OK.

Sync your PC with your Windows Mobile, iPhone, Palm OS device – whatever (as long as it’s compatible with Outlook) - to transfer the holidays onto your smartphone.