Angie's List, a popular subscription-based contractor rating service, has opened a Des Moines chapter. For the time-being, they are offering a free one-year membership to new users. Angie's List members can post feedback on contractors they have used and search other members' comments. Right now, there don't appear to be many "rated" contractors but that will change as the membership grows.

From the Angie's List web site:

We opened our DES MOINES chapter of Angie's List on 1/11/2007. While we're getting started in DES MOINES, you can join Angie's List for one year free. This offer will expire in a few months. At that time, you can sign up for a monthly membership for $5.95 or an annual membership for $51.