I love Seth Godin. He manages to take complex ideas and make them simple. Either that, or he alerts us to simple ideas that should have remained simple, but people tend to make complex. He has written heaps of books, introducing concepts like the "ideavirus", "permission marketing", "purple cows" and more. (he also shares much of this for free). This TED talk from 2006 highlights the many things that are "broken" in our world. If something's broken, why not fix it? Very entertaining way to innovate.