I have never be good at sales. I am not sure why, but it requires either qualities or experience I do not have. Selling the book Start-Up was a good example! So when I had to organize a workshop on sales, I checked a few things including the following videos which I found interesting. Some are GREAT!
Steve Blank Engineers and Founders: The First Sales Team
Frank Levison Real Sales and Customers in Business
Just in case you missed the point: Businesses Must Have Customers
Dan Spinger: Negotiating with Customers and Clients
Guy Kawasaki Seed the Clouds and Watch the Sales Grow
Randy Komisar Exploring New Sales and Marketing Channels
Tina Seelig Classroom Experiments in Entrepreneurship
Last but not least, even if not really politically correct
Bob Parson : Build 3 Mega Million $$$ businesses