Very interesting article from the WSJ on how companies are handling user feedback online.
What should companies do?
Get involved in the conversation. Approach the consumer in an understanding, not angry, tone. You won't be able to buy up every negative domain or stop every comment, so the best thing you can do is be transparent. Approach the customer with open arms and see what you can do to help them.
Companies shouldn't fear the negative comment. They should embrace it. If people are worked up enough about your product to write negatively about it online, chances are they will be listening to you explain how you will right a wrong.