Pitching VCs: Present Flexibly
http://getventure.typepad.com/markpeterdavis/2007/09/keep-your-prese.html
When most entrepreneurs practice these presentations they focus on smoothing out the pace of the presentation. While it's good to practice and get comfortable with the content of your presentation, it's important to keep the order and pace flexible; I can guarantee that you won't go in the order or at the pace you expected.
-- This is something I can relate to based on our YC interview last year in Boston. We actually prepared a pitch thinking we'd actually have time to parrot it out. How wrong we were :) Well, at least we know what to expect if we get called again.