The Economist has a good example of customer feedback in this article Past rites – How companies can benefit from looking backwards as well as forwards. It talks about how companies are becoming more interested in their corporate history and how they communicate this to customers, employees etc.
It mentions the fruit smoothie company, Innocent (quote from their website: make lovely natural fruit drinks like pure fruit smoothies and fresh yoghurt thickies).
Innocent sold an initial batch of smoothies from a market stall in London. They asked customers to put their empty bottles into one of two labelled bins to indicate whether they should focus on their new venture or stick to their day jobs.
Just thought this was a great example of getting customer feedback, and giving the customer a sense of involvement in the company.