About.com
A guide to independence days in countries around the globe.
http://geography.about.com/od/lists/a/independenceday.htm

AGlobalWorld.com
Daily postings of the holidays that are celebrated for that particular day in all countries around the world.
http://www.aglobalworld.com/index.shtml

Bank Holidays of the World
This site informs you of all the days when banks are closed, due to religious or public events.
http://national-holidays.com/
http://www.bank-holidays.com/

Ebookers.com Calendar
An interactive travel calendar that highlights red letter days, festivals, parties and events around the world. Free to download.
http://ebookerscalendar.com/

ExpatNetwork
Click on country profiles and then pick a country for details of its national holidays.
http://www.expatnetwork.co.uk/

Global Calendar
International festivals, celebrations and holy days - monthly guide.
http://www.sonic.net/phoenix/1world.html

HolidayFestival.com
A wonderful site which details national and religious holidays around the globe.
http://www.holidayfestival.com/

Holidays.com
A guide to American holidays and celebrations.
http://www.holidays.com/

Infoplease
A country-by-country guide to national holidays around the world. http://www.infoplease.com/ipa/A0907876.html

Oneworld Alliance
Choose a city and then click on the link marked "Full Year" on the relevant page for a list of public holidays in destinations around the globe.
http://www.oneworldalliance.com/destinations/single/single_city.cfm?city1=13

World Calendar
Highlights both religious and secular holidays in 75 countries worldwide.
http://www.world-calendar.com/