In British tradition, it is the one day women can propose to men for marriage. According to Greek superstition, couples who marry on this day have bad luck. If you are born 29 February, are you 4 years old on the next leap year or are you 1 year?
What Is a Leap Year? Short animated video that explains the astronomy behind leap years. (Fantastic video short with the whole skinny on leap year, calendar time, and more. Really cool to watch anytime.)