For service rating website
Does your website specialize in the ranking of service in a particular industry or just generally? A .FEEDBACK domain will add a sense of credibility to your website.
For the Customer service section of your website
Let your service users know that you care about them by providing a very adequate customer service to them. And be sure of this through feedback you get from them through your website registered with a .FEEDBACK domain.
For review website
Create a website where you test and use a particular goods or service and write all you experience from your extensive test of the service or products. A .FEEDBACK domain name for such website will gain your more site visitor than a normal generic domain name.
For a polling website
Do you need people opinion on a particular subject matter? Why not create a polling website where people can vote for or against a number of notion or perspective. By that you can view any topic through the public eyes. Since such website is centered on the feedbacks you get from people through their votes. Using a .FEEDBACK ending for such website will attract more visitors.