Take advantage of custom audio content with podcasts, audio books and recorded radio shows.
Thanks to PC Magazine (2/12/09) this is a great iPhone tip for public speakers. Your presentation is in 10 minutes and you just realized that you forgot to print out your presentation notes. Don't want your laptop obscuring your face while you speak? Save your document with a large typeface in Word, e-mail it to your iPhone, and open the attachment on your phone. You can easily scroll through your presentation with a touch while you're talking.
See the rest of the iPhone Secret Powers at: http://www.pcmag.com/article2/0,2817,2340854,00.asp