Father's Day cards = $743M
According to this New York Times story (registration required):
Father's Day is the fifth largest card-giving day of the year, after Christmas, Valentine's Day, Mother's Day and Easter. The National Retail Federation, estimates that Americans will spend $743 million on Father's Day cards this year.
...American Greetings, the world's second largest greeting card company (after Hallmark), has a new line for "today's sophisticated dads." Promotional materials promise cards that "speak to men who are connected with the Internet, whose tastes include electronic sports cars and home fitness equipment; who appreciate brands like Louis Vuitton and Tommy Hilfiger." Hallmark promotes cards with "more direct, more personal, more 'real life' ways of expressing thanks, appreciation and love."