EnvStick USB temperature sensor
The EnvStick is cheap, homemade temperature sensor that plugs into a USB port. It provides a simple way to collect a roomโ€™s ambient temperature.The EnvStick shows up as a serial port - a COM port on Windows boxes. You can see the typical output (on a program like Hyperterminal) - it waits a specified number of seconds, spits out a temperature reading, and starts waiting again. If you press โ€œpโ€, you can set the number of seconds in between each temperature reading.
   EnvStick USB temperature sensor
at www.camelspit.org