It's the smart shower, it can tell you how hot the water is and remember how you like it. Richard is using the LM35 temperature sensor, a CA3140 op-amp to amplify the voltage, and an 8 bit DAC to convert the temperature. A Stamp II is the controller. The servos are 142 oz-in units. Room Temperature Control by Sean Newman Sean proposes to measure the temperature of a room with a TMP04 sensor and turn on a fan or open the window as needed.
Energy conservation is of primary importance.