Someone said that today, Leap Day, is also Sadie Hawkins day. This is not actually true. Actually, Sadie Hawkins day is in November, most traditionally, and it originated with a girl whose father organized races where the girls chased the boys through the town and got to "keep" a boy, if they caught him.
Leap Day is LIKE Sadie Hawkins day, only more so. The tradition is that Queen Margaret of Scotland decreed that on Leap Day, women could ask men to marry them. Indeed, if a man said no, he had to pay a penalty of one pound or a pair of gloves or a silk dress...depending on his station. Women, however, had to give fair notice of their intent by wearing a red petticoat. If the woman did not display at least a corner of the red petticoat before asking, the man did not have to pay the penalty. He also didn't have to pay if he was already engaged.
Although this was not an actual law, it is a pretty established tradition. You can find postcards & such celebrating the fact - picturing Victorian women asking fathers for their son's hand in marriage, etc.
These fun facts are brought to you by the "Hannah was bored at her job today" committee, bringing useless but timely information to slightly interested people since 9AM this morning.