One of the highlights of the Zbrush Summit was the presentation by artist Danny Williams.
He has a really great, relaxed style. He is a good teacher. Inspiring and informative and really into learning how to do things as well as showing others how to do things.
And his art is cool too! Check out his site at: http://pointpusher.artstation.com/ and check the Pixologic site for a little more information about him: http://pixologic.com/summit/presenters/#williams