EMail Address Crawler 1.8.0 by CySlider has to be my new favorite Thunderbird AddOn:
https://addons.mozilla.org/en-US/thunderbird/addon/9995
The description is rather straightforward:
Automatically fill your address books or send mass mails with e-mail addresses extracted from all your e-mails.
It sounds like something a good person wouldn't do, doesn't it? Lose their addressbook, I mean.
But if you do, and you're a Thunderbird user, this little gem can save your life, not to mention your hair!
