Last week I was talking with Scott MacGregor about what I thought was a missing feature in Thunderbird -- the ability to forward several messages as one. We agreed that the feature would be useful and I said I'd file a report. The next day, David Bienvenu, the other Thunderbird lead, exlpained to me and Scott that this was already possible. The trick is that you have to forward as attachment.
So, if you're like me and you've set your default for forwarding to "Inline", and you want to forward a conversation or other series of emails, just control select the various messages, go to the Message menu and click on Forward As, then select Attachment.
If you've got other nifty Thunderbird tips, please share them here.