Improving Teaching Through Feedback

Here's an excellent article (actually an excerpt from the book Mastering Contemporary Preaching) about improving preaching and teaching through feedback.

Somewhere I heard the phrase "feedback is the breakfast of champions."

I personally both want and don't want feedback. And I need useful feedback that can help me get better. If all I hear is "Thanks Glenn that was great!" then I don't know what to work on. I need specific information about what I should start doing, what I should keep doing, and what I should stop doing.

How many of you have established a systematic feedback mechanism? This is an area that I would glad to hear more about what's worked, what hasn't.