This is a pre-wired and waterproofed version of the DS18B20 sensor. Handy for when you need to measure something far away, or in wet conditions. While the sensor is good up to 125°C the cable is jacketed in PVC so we suggest keeping it under 100°C. Because they are digital, you don't get any signal degradation even over long distances! These 1-wire digital temperature sensors are fairly precise (±0.5°C over much of the range) and can give up to 12 bits of precision from the onboard digital-to-analog converter. They work great with any microcontroller using a single digital pin, and you can even connect multiple ones to the same pin, each one has a unique 64-bit ID burned in at the factory to differentiate them. Usable with 3.0-5.0V systems. 

The only downside is they use the Dallas 1-Wire protocol, which is somewhat complex, and requires a bunch of code to parse out the communication. If you want something really simple, and you have an analog input pin, the TMP36 is trivial to get going.

A 4.7k resistor is required as a pullup from the DATA to VCC line when using the sensor.

Dallas Temperature Control Arduino library

OneWire Library.

Features

• 9 to 12 bit selectable resolution
• one digital pin for communication
• Multiple sensors can share one pin
• Query time is less than 750ms

Specification

• 3.0V to 5.5V input
• Temperature range: -55 to 125°C (-67°F to +257°F)
• ±0.5°C Accuracy from -10°C to +85°C
• 3 wires interface:
  • Red wire - VCC
  • Black wire - GND
  • Yellow wire - DATA
• Stainless steel tube 6mm diameter by 30mm long
• Cable length: 90cm

Adafruit Tutorial:

Adafruit's Raspberry Pi Lesson 11. DS18B20 Temperature Sensing
Measure temperature with your Raspberry Pi using the DS18B20