Until fairly recently, when designers wanted to test an idea or design, they sought out an outside usability agency or, rented a room, some expensive equipment and recruited users to come into an artificial environment to participate in a usability study. In the past few years, technology has become available that has brought the cost and complexity of user testing down to a level where it is available for anyone. In addition, it allows designers to be exposed to users, in their native environment, not a sterile lab across town. You can run a test in only a week for less than a few hundred dollars.