This is a tidy analog temperature sensor with a functional range of -40°C to +125°C
The TMP 36 series of temperature sensors are pretty handy. This one comes in a tidy TO-92 transistor-like package. Feed it Vcc and ground and you get a precise analog output indicating the temperature in degrees C. The accuracy is pretty good too, being ±2°C over a range of -40° to +125°C.
The output is 10mV per °C, with 25°C reading 750mV. Tie this to your microcontroller's A2D port, and you are set to go!