Pi Day falls on March 14th because of the first digits of Pi- 3.14. Another geeky boon is that the holiday also happens to be the birthday of one of science’s biggest rock stars, Albert Einstein. Many cities and institutions of geekery, like the Maryland Science Center, hold celebrations to party down on the mathiest day of the year.

Pi has many uses in the mathematical world. Perhaps the one most people remember is its use for finding the circumference or area of a circle. The symbol is also used for the unit of radians another format for writing the degrees of a circle. Pi is also the name of a popular Indie film about a mathematician that sees the same digits repeating throughout his life and tries to determine their significance.

The symbol for the Pi was first put into use by mathematician William Jones in 1706, but only became famous after Swiss mathematician Leonard Euler used it in 1737.

If you need inspiration, the folks at PiDay.org have lots of stuff to play around with, including links to Pi-related videos.

In honor of the day Google has updated its logo on the Google.com website with a special tribute to Pi Day 2010. In addition, Maryland Science Center, Discovery Science Center and San Fransisco Exploratorium are just a few of the places throwing "Pi parties", so today you can "have your Pi and eat it too!"

I can’t remember Google ever having a special “doodle” or logo for Pi Day, but that has changed today, March 14, 2010.