Moty22.co.uk has a PIC16F628A based thermometer using DS18B20 digital sensor.
Counter based on PIC16F628A . Included C code and circuit diagram. Displays -55 to 125 centigrade. The temperature is read every 15 seconds, can be changed in the code. The math is using integers to calculate the degrees and the tenths of degrees are calculated separately.
The 7 segment LED is common cathode, 4 separate digits can be used with segments a to g linked.
4 Digit Thermometer using DS18B20 and PIC16F628A – [Link]