The Weather Channel Firefox addon thingy (...do da wubba bingo) -- application, I mean is way cool. Right there on the status bar of the browser, current conditions and immediate forecast.
Occasionally, however, it does this:
and I have to run to the window to make sure it's not the end of the world or something. So far, it has only been glitches in the programming. If it ever turns out to be something else, I'll let you know.