if you don't want to use singel chip to build your own thermometer, you can use LM35 or LM335. The temperature range between 0 - 150 Celcius or Kelvin. And you can use any ADC (I ever use ADC0808,and my own ADC-I build by my self)to get the value of the temperature.
LM 335 or LM35 it's very linear the sensitivity is 10mv/Celcius or 10mV/Kelvin.

Have Fun.