This year, January 20, 2007 marks the beginning of Muharram. According to this entry in Wikipedia, Muharram is a Shiite branch of Islam festival:
Many of the male participants congregate together in public for ceremonial chest beating (matham) as a display of their devotion to Husayn and in remembrance of his suffering. In some Shi’a societies, such as those in Bahrain, Pakistan, India, Afghanistan, Lebanon and Iraq, many male participants practice self-beating/mutilating of their bodies and those of their children using knives or razors swung upon chains . Even mothers believe that they must inflict some form of flesh wounding on their own children to participate in this ceremony. The Mainstream Sunni Muslims consider such practices as offensive to their Islamic faith. In fact, the controversy over those practices have been the source of many clashes between Sunnis and Shias.
A picture may be worth a thousand words, a video, millions. Thanks to BabbaZee at LittleGreenFootballs.com for finding this link: (Graphic depictions of 7th Century mutilation)
(Less than one minute long)