I'm definitely one of those speakers who can just write something down and present it in front of an audience cold. I usually need to rehearse about a half-dozen times before I'm comfortable enough so that I don't need to read from the printout of my slides exclusively. I wish I was more like my hero,
Rob Wunderlich, who seems to make presenting effortless. Then again, he was a Lotus instructor for years, and even was a radio DJ at one point, if I remember correctly.