Garr Reynolds writes a great blog, Presentation Zen, which I recommend highly. In his most recent posting, Ira Glass: Tips on Storytelling, Garr summarizes the points made by Ira Glass, famous for This American Life on NPR, on a recent video.
Don't miss this one. Ira Glass is one of the best broadcasters and storytellers I've heard.
Podcasts of This American Life are available on iTunes.