Here are my favorite Firefox Add-ons:
ShowIP
https://addons.mozilla.org/en-US/firefox/addon/590
ScribeFire
https://addons.mozilla.org/en-US/firefox/addon/1730
ChatZilla
https://addons.mozilla.org/en-US/firefox/addon/16
Forecastfox
https://addons.mozilla.org/en-US/firefox/addon/398
Bookmarks Sort andsync
https://addons.mozilla.org/en-US/firefox/addon/2367
Google Bookmark sync
https://addons.mozilla.org/en-US/firefox/addon/4530
https://addons.mozilla.org/en-US/firefox/addon/60
https://addons.mozilla.org/en-US/firefox/addon/748
https://addons.mozilla.org/en-US/firefox/addon/1865
https://addons.mozilla.org/en-US/firefox/addon/1512
https://addons.mozilla.org/en-US/firefox/addon/1843