Here is a link to a relatively long interview/discussion describing how the Net Promoter approach is used to generate closed loop feedback and learning at Zappos. While it's not the slickest video ever, it is HIGHLY informative, describing the approach in some significant detail.
Zappos does a very nice job of creating real closed-loop feedback and using it to drive learning and improvement for customers. The company was built on creating wow experiences for customers, and they have succeeded in using this to achieve very high customer loyalty, strong word-of-mouth and profitable organic growth with very little advertising.
Video: Zappos CLT and NPS (approx. 17 minutes)