http://www.ninfinger.org/~sven/rockets/rastrocam.html Another camera payload made from the Estes Astrocam.
http://www.ninfinger.org/~sven/rockets/payloadfaq.html The F.A.Q.'s from rmr about payloads in rockets.
http://www.nar.org/NAReduc.html NAR's Student Experimental Payload (S.E.P.) program. The NAR will help guide you through the steps necessary to build and fly a complext electronic payload.
http://www.cmass.org/uploads/Robert.Galejs/timer.html Plans for a tiny timer payload that will fit into a 13mm tube. (high school level)
http://www.cmass.org/uploads/Robert.Galejs/Magnet3.PDF Magnetic Apogee Detection Sensor Article (PDF format). This device uses the earth's magnetic field to tell you how high your rocket flew. (high school level). There is also a tips section to give some guidance on how to build the device.
http://www.alaska.net/~aleckson/magnet.htm A modified version of the Magnetic Apogee detector.
http://modelrockets.8m.com/altigi.zip Text instructions for building an altimeter.
http://members.aol.com/GCGassaway/Sunguidance.htm Building a sun seeking rocket with active guidance.
http://www.jcrocket.com/altimeters.shtml A comparison of different commercial rocketry altimeters; both barometric, and accelerometer based.
http://www.dehate.com - Altimeter that you can build yourself.