The concept of pi refers to the constant ratio of the diameter:circumference of any circle; irrespective of the number of degrees contained within that circle. An article in the "Science in Ancient Artwork"-Series by Charles William Johnson.
Dr Math answers over 60 questions submitted by people about pi including questions on the Bible's relationship to it and its relationship to trigonometry.
An open source endeavor for the calculation of this constant. Describes the project, the implemented algorithms for calculation and software downloads.