Measuring temperatures is one of favorite tasks among microcontroller hobbyists. Usually there are several types of sensors used including 1-wire DS18B20, thermistor resistor or linear LM35 which outputs voltage linearly related to Celsius.
Gaurav have constructed LM35 based temperature meter that involves PIC 18F458 microcontroller which basically reads LM35 value wit 10 bit ADC, calculates temperature and outputs to Nokia3315 LCD connected via SPI interface. This is very straight forward solution with no additional features. Sometimes you just need one of those.