Here just a selection of links on the subject of pi.

Information on pi may be found in the online encyclopedia at

Friends of Pi
„The goal and task of our group is to hold high and further the spirit of pi.“

The History of Pi
A thesis from a mathematics faculty on the history of the approximation of pi.

English-language website

Article on how to calculate pi to the 1-millionth decimal point using a computer.

Pi Search
Website where one can search for numbers occurring in the first 3.2 billion decimal places in pi.