I highly recommend Patty Seybold's new book "Outside Innovation: How Your Customers Will Co-Design Your Company's Future." (See Required Reading.) In it she states, "you no longer win by having the smartest engineers and scientists; you win by having the smartest customers."
I know, it sounds like something new for small business owners to worry about—smart customers! But don't be dispirited. Small business owners actually have a 'leg up' in this arena. They are closer to their customers and can really encourage and use feedback. I also touch on this in my free ebook, Small Business 2.0. which deals with how small businesses can utilize the latest tools to grow their business.
The key take-away here is that if you aren't figuring out how your customers can participate in the growth of your business, either by collaboration or evaluation of products and methods you are wasting a great resource.