ForecastFox - Firefox
Extensionhttps://addons.update.mozilla.o
rg/extensions/moreinfo.php?id=398&application=
firefox

This is quite a cool little extension. Received some very good reviews and I really like it.
I set it up to automatically scroll through the area of various family and friends around the country so that I can just glance down every once in a while to see what their weather is like.