Athletics tracks are always run anticlockwise. Does this favour particular runners? Races could surely be run either way, so why never clockwise?Peter Hallberg, Stockholm, Sweden(Image: dlritter, stock.xchng)
In military parades it seems to be the tradition to march so that you have the king or general on your right hand side when passing him. This is probably both due to the salutation by the right hand and that it's easier to present weapons (held in the right hand) this way. On an arena this translates into a counterclockwise march.
I don't know if this have something to do with it but, in most ancient cultures, anti-clockwise is considered the natural movement of the universe (see for example the Swastika), and it's supposed to be a pattern of that movement in nature like, for example, the flow of the blood on the circulatory system.