September 21, 2010 is the International Day of Prayer for Peace.  The World Council of Churches reports:

The International Day of Prayer for Peace offers an opportunity for church communities in all places to pray and act together to nurture lasting peace in the hearts of people, their families, communities and societies. The idea was proposed in 2004 during a meeting between WCC general secretary Rev. Dr Samuel Kobia and UN Secretary General Kofi Annan (press release), and coincides with the UN International Day of Peace. The Day of Prayer is one of the initiatives of the WCC's Decade to Overcome Violence.

Click here fore more information.