Through the 2008 Summer Games, the U.S. has never won a medal in handball, table tennis, rhythmic gymnastics, and badminton. According to the olympic website, the US has 3 events it has never won a medal in----I know one of them is Handball, but do not know the other two. Through the 2006 Winter Games, the U.S. has never won a medal in biathlon and nordic combined.
The circle with the arrow means male, and the circle with the plus sign means female. the circle with a plus-sign is used as the zodiacal symbol for the planet Venus. It is the female and male sign. the one in your question with the top pointing up is male, and the one with the cross pointing down, is female.
The circle represents the cycles of life, and the four axis points represent the four directions of our physical world, north, south, east and west. Each of the 4 directions also represents one aspect of our selves: North is the Mind, South is the Heart, West is the Body and East is the place of Spirit.