The Three-Toed Sloth presents this excellent advice on seminar presentations.
It's advice that's heeded far more often by Statisticians than by Economists, in my experience.
The only things I'd add are : One hour is plenty of time - 1.5 hours is too long for most attention spans; and we go to seminars to listen to the speaker, not to listen to members of the audience interrupting the speaker.
© 2012, David E. Giles