I have wireless broadband for my car. I also have a gps unit. So I decide to combine the two and get current weather (well not second by second but relativly current.) I wrote a program for Linux in Python using wxpython and the python-gps libraries. It basically contacts noaa and requests the weather based on the location retrieved from your gps.
I wrote this for carPCs but I guess you could use it on a laptop while you are traveling.