This one time, I was trapped in a bookstore with nothing to read. After I broke out, I would have had to wait for the entire 15 minute drive home before I could get a new book on my Kindle... but free 3G really saved my bacon that day.
Actually, I believe I used the 3G on mine immediately after I got it—just to verify everything worked as advertised—and haven't used it since (and I don't have Wifi on mine either).