BooRah searches the web for mentions of restaurants in blogs and websites and analyzes the languages in the post to determine whether the reviewer was giving the restaurant a thumbs down (boo) or a thumbs up (Rah). The amount of Boo's and Rah's a restaurant gets are tallied up on the site and then the restaurant is given an overall score. BooRah users can add their own tags to a particular restaurants page, and can weigh in by giving a particular place a Boo or Rah directly on the site.
Currently the service is limited to just 20 large metro areas, with more expected to be rolled out later on. If you're fortunate enough to live in one of those areas you can search for restaurants by your particular neighborhood, and sign up for an RSS feed for your area so you always know about the latest place in town.