Discovered On The Fly
I just learned through good ol' 'sperience that a Firefox tab can be dragged below the tab bar and what was formerly a tabbed window, becomes a new window atop the window the page had been in. I don't know how useful this is but since I happened upon it, I thought I'd share. 'Cause I'm that kinda guy.
By the way, this only works if there's more than one tab in the original window. Seems obvious but I thought I'd say.