You have just released a shiny new widget. Or launched a cool information product. Now you want to know what people think about it. Why not blog about it and invite feedback?
A blog is a cool way to talk about some uncommon uses for your products and increase consumption. Launched a new software that makes cool Flash videos? Why not make a blog post that explains how people can use it to increase their sales or tap new prospects? What do the people think about it? Are they liking it? Do they find a particular option confusing? Have they located a bug?
If you invite people to post comments about their opinion on your shiny new product or service, they may let you know what they find great about it or what needs fixing. Take the feedback openly. It is OK if they have discovered some bugs. As long as you fix the bugs promptly, it is not very bad to have problems. This is the cheapest way to get frank opinion and feedback from the market. Incredibly cheaper than appointing some survey agency to go out and interview users, compile a report and then send to you after may be, months. Try it!