Analog TMP36 Temperature Sensor
Now available from PMD Way are Analog TMP36 Temperature Sensors in pack sizes of 10, 30, 50 and 100 units.
The TMP36 is a wide range, low power temperature sensor that outputs an analog voltage that is proportional to the ambient temperature.
To use, connect pin 1 (left) to power (between 2.7 and 5.5V), pin 3 (right) to ground, and pin 2 to analog in on your microcontroller.
The voltage out is 0V at -50°C and 1.75V at 125°C. You can easily calculate the temperature from the voltage in millivolts: Temp °C = 100*(reading in V) - 50
See the webpage for datasheets and more information. Interesting tutorial on the TMP36 by adafruit.