As a leapling (one who is born on February 29th), I do not have a birthday this year. And it is on this "off" years that I did some research to remember why we even have Leap Years as part of our calendar.
So first, defintions... a leap year occurs when an extra day (the 29th) is added to Februrary every four years. This was done, according to this very interesting article from National Geographic, "to keep the modern calendar in line with the celestial cycles that frame it."
For centuries, many cultures around the world have added extra days to their calendars to round out the discrepancy of the earth orbiting the sun every 365.242 days. The Julian calendar had a glitch that drifted the year off by ten days, which resulted in annual events and holidays landing out of the seasons with which the celebrations were intended. Pope Gregory XIII addressed this off-kilter situation in 1582 by introducing his calendar which instituted the addition of a day in Februrary every four years.
Folklore was created to explain leap years. One such is the legend that women could propose marriage to men only on leap years. If the ladies' offer of her hand in marriage was declined, she was compensated in the form of money or finery, such as a silk dress or a fine pair of gloves. The details of these urban myths cannot be substantiated by historical documentation however "proof" of the legend exists. In my research of these myths on Google, I came across a number of delightfully cartoonish postcards:
I'm sorry to say ladies that you will need to wait until next year to send one of these cards to your fellow as the next Leap Year isn't until 2012.