Whenever I see a weather "app" I always think: "This is really a weather <i>display</i> utility" and then wonder about the quality / longevity of the service it depends on and how the information is provided.<p>What would interest me is an implementation that allows you to plug in different weather backends, so that having an API key to worldweatheronline, or screen-scraping weather underground, or building a bridge to your serial-port connected weather station all can target the same interface; to provide current conditions/historical conditions, a forecast, etc.<p>Are there standards for this, or is it mostly ad-hoc, the whim of the sites or commercial services which aggregate information and provide forecasts?