Another nice piece about estimates. This time for the tough times when you're asked a quick ballpark number. The best piece of advises in there: know when you shouldn't do it at all, and, if you go for it sound vague.

I'd even add "you can never be to vague". Even if you go for "a few weeks, maybe two or three" very often people here "two weeks". Don't hesitate to hammer down the uncertainty in all this.