The Birthday Calculator is a fun little Web site you may enjoy trying with your kids. Enter a birth date and year, and it displays all kinds of information about that date, including the phase of the moon, dates of holidays that year, U. S. population statistics then, and the number of months, weeks, days, hours, minutes, and seconds old you are now. My favorite? The number of BTU’s that will be produced by the candles on your next birthday cake, and how many ounces of water they would boil. (Thanks to Lifehacker for the tip.)