Well,
Welcome to Weather Underground : Weather Underground has a bunch of "API"s (programmer speak for 'connections') that will let you get tons of info, right from the net.
If you have a GPS, and it's getting so easy as to wonder 'why not?', you take the coords from it and plug them into a URL over at WeatherUnderground. What it returns for you is a load of information RV travelers would like to have, generally speaking.
It returns country, state, county, and city, as well as local webcam URLs, forecasts, and weather alerts, and a host of other details. This isn't earth-shattering, but I remember times we wondered which state we were in, exactly, because it would have to be one of two.
Knowing this also allows you to bring up GPSDrive, an free application for mapping your trip. It'll download maps for the whole thing, really helpful for a multi-day journey. And of course, there's also Google.
What the annunciator would do is be made aware of severe conditions (thunderstorms, frost warnings, anything you can measure like low propane levels WITH a frost warning, in the daytime while they're still open at the camp store...) and anything else you can think up.
Again, it's all open source; as it gets created, you can do what I did, or better yet, collaborate with me to make our mutual units better, and help hand off the idea to other people, too.
Right now I'm missing my old annunciator; I'm inside taking care of Mom, not out in the trailer hearing the passage of hours and half-hours and getting historical notifications every morning with the rise-n-shine alarm. I really should get back in there and _build_, but other things have come up.
