Describe XBee here.
http://nootropicdesign.com/projectlab/2009/11/01/wireless-temperature-sensor/
http://nootropicdesign.com/projectlab/category/xbee/
http://www.ladyada.net/make/tweetawatt/index.html
http://wiki.groundlab.cc/doku.php?id=xbee_code
http://ftp1.digi.com/support/firmware/93009382_D.txt
http://www.sparkfun.com/tutorials/257
http://www.sparkfun.com/products/9132
http://code.google.com/p/xbee-api/wiki/XBeeUseCases
http://arduino.cc/playground/Main/InterfacingWithHardware#Storage
http://arduino.cc/playground/Main/EEM12L-32AKWhMonitoring