In the Zoroastrian religion, today is Zarathosht Diso, the anniversary of the death of the prophet Zoroaster. It is a day of prayers, along with discussions on and remembrance of the prophet's life. This site provides more information.
Today is also the beginning of Kwanzaa, the pan-African celebration created by Maulana Karenga and first celebrated in 1966-1967. As the official site indicates, "As an African American and Pan-African holiday celebrated by millions throughout the world African community, Kwanzaa brings a cultural message which speaks to the best of what it means to be African and human in the fullest sense." Here are the seven core principles of Kwanzaa: http://www.officialkwanzaawebsite.org/NguzoSaba.shtml