orz is a Japanese emoticon that represents a person kneeling, head bowed to touch the floor. The "o" is the head, "r" is the body, arms, and hands, and "z" is the knees and legs. It is usually used to indicate failure, but it can also mean worship or humility.
It is a very commonly-used emoticon wherever Japanophiles are found, including the English forum 4-ch.