We've just launched a new service called Startup Surveys (http://www.startupsurveys.com) where we can help to test your business idea and get some real user feedback on your idea before you launch (obviously I am affiliated).  Basically we can survey about a 500-1000 people from around the world and get you some feedback - we also offer users to opt-in voluntarily to an email list to your service if they are interested in using the service in the future.  The idea is that you can use these initial users as your potential customers!

If you are launching a business or new products or services, you will want to focus on interviews and surveys with your prospective clients and partners. Usually, primary research, like surveys or focus groups, can be conducted at a low cost.