My current Firefox extensions / add-ons (because I'm bound to forget). I have deleted previous posts saying the same, as I really write these for my own benefit later on (like, when I forget to backup my profile and reinstall).

Adblock Plus
Delicious Bookmarks
FireGPG
NoScript
Read it Later
Personas for Firefox

Thunderbird extensions (installed from the Ubuntu repos)

Enigmail
DispMUA
Traybiff