rn for FoxClock(It supports Arabic Firefox...I think..)
https://addons.mozilla.org/en-US/firefox/addon/398 For Forecastfox.
https://addons.mozilla.org/en-US/firefox/addon/220 Flashgot, It supports dozens of download managers.
I listed foxclock because I thought some may want to know diffrent time zones without switching to a diffrent tab(Let's say I want to know what time it is in the pacific region of the US because an online buddy lives there) You can also place the clocks under the addon icon to tidy up the browser's status bar.
I don't know how forecastfox is better than other weather addons or sites but I thought that some wanted to know about it.
All I can say about Flashgot is that it's Great and that you should check it's description and try it out for yourself ;)