Letting users control your site can be terrifying at first. From day one we were asking ourselves, "What is going to be on the front page today?" You have no idea what the system will produce. But stepping back and giving consumers control is what brought more and more people to the site. They have a sense of ownership and discovery at the same time. If you give users the tools to spread and share their interests with others, they will use them to promote what is important to them.
Source: Business 2.0: How To Succceed: Let the Users Run the Show: http://money.cnn.com/popups/2006/biz2/howtosucceed/11.html
Contributed by: ~C4Chaos