I've said it before, but I'm going to say it again: I think the iPhone would be a lot cooler if it had a temperature sensor on it. In terms of technology, all it is a single temperature controlled resistor (called a thermistor), probably worth about 5 cents. But it would be cool to be on a patio and be able to see how hot it is. I also think that if everyone opted in to given this data to a central repository, that it would be possible to increase the accuracy of our existing weather models a great deal. Currently weather models are primed using sparse initial conditions. For example, in Vancouver, ...