A friend in San Francisco in a heated dispute with a landlord who was going to withhold her damage deposit said, “Do you hear that clicking sound?  That is me Yelping that you are a rip-off landlord.”

The deposit was returned immediately. This is the power of Yelp.com.

Now that’s something to Yelp about.

I first discovered Yelp when my daughter got a movie review, advice on the best seats in the theater and ratings for nearby Thai food from hundreds of San Franciscans “in the know” – all in under a minute  – from the comfort of her desk at work, all while chatting with me on the phone.

32 million people share reviews on Yelp every month. Some – as in the case above – view it as a tool for exposing poor business behavior.  It is a way for consumers to band together for justice. Others share local knowledge and send more customers to deserving but under-recognized businesses. Most, like my daughter, use it like a local, up-to-date source for what’s hot and what’s not.

To search, just type in the kind of business you seek (anything from shoe repair to Moroccan food) and an indicator of location (zip code, neighborhood, etc).  Each business in your search result is listed with a 5-point rating (reviews from visitors to Yelp), and contact details.

To contribute an opinion on Yelp you must first be approved by a moderator.  Once inducted, you become a part of your local Yelp community, a kind of social network. If you are an especially reliable and prolific “Yelper,” you may even be invited to a Yelp-sponsored party celebrating your contributions. The people behind Yelp.com want to encourage Yelpers (hence the parties) and grow their listings (hence the credit they give to reviewers who submit the first review of an establishment).

Yelp began and ‘took off’ in San Francisco.  It is now in Boston, Chicago, New York, Washington, D.C., San Diego, Los Angeles, Canada, France, Ireland, and the UK.  It is  beginning to offer reviews in smaller towns like Greenwich, CT.

Yelp has been in the news recently for rejecting an offer from Google and its co-founder, Russel Simmons, has just left – but the Yelping continues.