This I2C digital temperature sensor is one of the more accurate/precise we've ever seen, with a typical accuracy of ±0.25°C over the sensor's -40°C to +125°C range and precision of +0.0625°C. They work great with any microcontroller using standard i2c. There are 3 address pins so you can connect up to 8 to a single I2C bus without address collisions. Best of all, a wide voltage range makes is usable with 2.7V to 5.5V logic!
Unlike the DS18B20, this sensor does not come in through-hole package so this small sensor has been placed on a breakout board PCB for easy use. The PCB includes mounting holes, and pull down resistors for the 3 address pins. Adafruit even wrote a lovely little tutorial and library that will work with any Arduino compatible. You'll be up and running in 15 minutes or less.
Some quick specs: