The Arduino seems the ideal platform for making your own medical monitoring system. Your temperature, heart rate, respirations, blood pressure, weight and O2 content of the blood are all measurable and loggable. Here are a few links to get you started, but email me at sspence@green-trust.org with more links to this application.
http://www.wonderhowto.com/how-to-make-infrared-heart-sensor-286365/
http://danjuliodesigns.com/sparkfun/hrmi.html
http://jdesbonnet.blogspot.com/2010/05/using-arduino-duemilanove-as-quick-and_25.html
http://www.ladyada.net/learn/sensors/tmp36.html
