Milkman said:
For example, if there was a flood watch for the area you are driving into a warning would flash on the display.
This is also one of my long term plans. If you've seen a relatively modern "weatheradio", you've seen how most come with LCD displays now, and actually show you in text any watches or warnings in effect. This is thanks to a system called SAME alerting, Specific Area Message Encoding. Its an improvement over the old days of "there's a thunderstorm in the northern half of New Jersey." Every county in America has been issued a serial number of sorts, and every type of watch or warning has also been issued a type code. So whenever a watch or warning gets issued for a county, NOAA weather radio puts out short data bursts listing the counties involved, the types of watches or warnings, and the duration of the watch or warning period.
Since the nav knows where you are located, it should be able to do a lookup in a database for the NOAA frequencies that cover your current location (and perhaps surrounding counties), and tune a small receiver to scan the appropriate frequencies. Then, as alerts are issued, update the display in real time, lighting up an affected county in yellow, red, light or dark green just like they do on the Weather Channel. With GPSDrive for Linux, you can overlay stuff over a map (but not do routing - also good for mapping open wireless LANs). Now, pair that up with open access via 802.11, and the system could react by not only lighting up the affected county on the map, but also start looking for open wireless to pull down an updated radar loop for your area. I know I sure could have used that when I came across the tornado in Missouri. I kept hearing long lists of counties being read off for tornado warnings but I had no idea where they were relative to us.
To date, I have not found a software SAME decoder, but I'd bet the PIC-E from tapr.org could be programmed to decode their data transmissions, since it already does 1200-baud packet for APRS applications.
Another of the many reasons I want a full PC in the car. Does anyone think there's a chance we'll be able to pull an NMEA stream out of our Nav systems? That would help *immensely* in planning apps for a carputer.