http://www.exploratorium.edu/pi/
The original celebration site! Check in often to see what they are planning for this year!
http://mathforum.org/teachers/middle/activities/pi_day.html
Directions for making a pi day necklace using pony beads.
http://www.facade.com/legacy/amiinpi/
Am I in PI? This is a calculator where you enter your birth date (or other important dates) and find where in pi that series of digits occurs.
http://www.notsohumblepi.com/
Pi-RATES — a funny way to look at PI.
http://www.pbs.org/wgbh/nova/teachers/activities/3010_archimed.html
Archimedes’ way of computing PI
http://www.mathematicianspictures.com/PI/PI-OF-THE-MONTH-CLUB.htm
Pi of the Month Club. Watch the huge PI drop on March 14.
http://www.mathwithmrherte.com/pi_day.htm
Exceptionally fun and different celebration ideas from Mr. Herte.
http://www.cafepress.com/pi1000
PI apparel.
http://www.piday.org/
Official Pi Day
http://www.mathgoodies.com/Webquests/pi_day/
Pi Webquest