You might want to post the barometers reading to the hundredths of an inch (30.34 instead of 30.3)
are you planning to including Weather Underground's real-time stations to WWL or the Firefox entension?
Yes -- and the extension will eventually be upgraded to include those stations.
Also can you make the temperature on the toolbar bigger or bolder to make it more visible?
I tried to pick a font size that would appeal to most people. While bigger and bolder would be possible, I don't think it would work for everyone. It looks like this will probably have to be added to the Options window.