As it turns out, 2006 is the 300th anniversary of the first use of the symbol

**π**was used to represent the ratio of the circumference of a circle to its diameter, in the publication, “Synopsis Palmariorium Mathesios”, written by William Jones in 1706.

In case you're at a loss as to how to celebrate, take a look at these Pi Day Resources and, of course, the obligatory Wikipedia article on π.