Am I Hot or Not
Sure, it's not the dream system with computer-controlled vents on the furnace and a genetic algorithm to optimize heat-flow, but it is pretty damn cool. This system makes use of Dallas Semiconductor Digital Thermometers to monitor temperature throughout the house. Hopefully the fellow running the project will put up the source to the Linux driver he has running the sensors. This project ties in nicely with the question posed by a recent Ask Slashdot as well.
By the way, the interesting thing about these sensors is that they are actually network devices, each with it's own unique ID. You can address each of them separately over the "1-wire network" and get their temperature reading. Also note, that these sensors directly give you a temperature reading, not current or some other reading. So, they do not require any calibration and are a breeze to use.