Annoying as crap that Mozilla won't build this feature into FireFox and that we have to rely on flaky developers like this for updates (that, evidently, will never come).
And yes, I know that one can drag the text to the tab bar (but it's awkward as hell) and no, other solutions here do NOT work for FF 3.6.
Memo to FFox developers: How about gettin' off your fat asses and giving your suffering users the same functionality that your competitors give to theirs with this feature? It's damned useful and it can't be hard to do.
End of rant