For the last talk in my Top 10 sustainability related TED Talks list, we have Amory Lovins with "A 40-Year Plan for Energy." Lovins is the chairman of the Rocky Mountain Institute, a consultant, a physicist, and widely regarded as one of the most knowledgeable people in the world on the subject of energy and how we use it.
In this 27 minute talk (unusually long for TED) he lays out in plain English how we can fundamentally change the way we use and generate energy. The recipe is really quite simple: efficiency first so we are using much less, and then the transition to renewables is much easier.
As Lovins says in this talk, "our energy future is not fate, but choice." Here (and in many presentations like this one) he lays out a clear and simple road map for how to make the right choices.