Angie's List is not free but my friends and I have had great success with the service. The basic package — after a $10 signup fee — is $5 per month or $50 per year. There are no anonymous reviews and Angie's List uses a "certified data collection process" to ensure that companies and providers cannot report on themselves or on their competitors. The "Complaint Resolution Team will intercede if a home repair or health experience goes bad" and companies and providers respond online to reports, so you get both sides of the story. Discounts from highly rated local companies are also available.
According to its website, Consumers’ Checkbook / The Center for the Study of Services is an independent, nonprofit consumer organization founded "to provide consumers information to help them get high quality services and products at the best possible prices." Checkbook is supported by subscription payments and publication fees. It does not accept donations from businesses and its publications contain no advertising. Subscribers can access a massive database of local companies and service providers, each of which is rated for quality as well as for price. You can also see the percent of customers who rate the firm "superior" on a survey for "overall performance".
Thumbtack.com is a free directory of providers that allows you "to vet, contact and book service professionals the moment you find them." Thumbtack claims to review every profile and checks professionals against the DOJ Smart database. I have never used Thumbtack but when I typed in a few search terms I was impressed with how user-friendly and unfussy the database was. The handful of searches I conducted did not turn up any service professionals who had been reviewed by other users, however. But my sample size was miniscule and I would love to hear from others if they have used Thumbtack to find contractors who had been reviewed and vetted by other consumers.
Finally, once you have narrowed down your list of contractors, run them by your local Better Business Bureau website in case anything unsavory turns up!
Have you made use of any of these sites? What was your experience? What other resources offer similar reviews and vetting services?
ALSO: How to Hire a Contractor