This code is derived from: http://www.arduino.cc/playground/ComponentLib/Thermistor and https://github.com/dingram/Nanode/blob/master/Ethershield_webserver/Ethershield_webserver.pde
It shows a live sensor reading from Analogue 0 on the webpage upon page refresh. The trick to getting this to work was to not use dtostrf() instead of sprintf() for the float to string conversion.