One of the things that makes our country so great is the rich diversity of people that desire to live in our communities.  As good customer service and relationship building is the key to developing long term clients, it's important to strive to understand and appreciate others.  One way is to learn and understand their customs, which shows respect, acceptance and understanding on our part. 

This includes holidays, secular and religious.  (It can also be incorporated as part of advertising campaign.)

Here are a few general holiday links you can reference:
Click here for Wikipedia list of holidays and special occassions celebrated in the United States every year.
http://www.holidays.net/

Here are resource links for information about religious holidays and festivals celebrated in the United States and around the world including calendars for important religious dates...
http://www.beliefnet.com/calendar/
http://www.religioustolerance.org/main_day.htm
http://www.calendarzone.com/Holiday/
http://www.smart.net/~mmontes/ec-cal.html
http://www.celebratetoday.com/callinks.html
http://www.calendarday.com/
http://www.index-china.com/index-english/chinese_holidays.htm


Many people are practitioners on various levels of Feng Shui and you may encounter Vaastu if they are of Indian background.

Does any one else have experience and/or resources that would further address and help us understand these or other related areas, especially if you were brought up in that custom or practice?