Online real estate site Zillow.com dares you to put your house on the market.

The company today rolled out what it's calling a "major upgrade" of its site that lets home owners and real estate agents post homes for sale at no charge.

The service update also includes a new feature to lure prospective sellers, the ability to post a Make Me Move price — the obscene sum that would entice even the most intransigent homeowner to take the money and run.

In a statement, Lloyd Frink, Zillow's co-founder and president, describes Make Me Move as "our twist on the traditional 'For Sale' sign." The feature allows homeowners to anonymously solicit offers via e-mail, presumably without the risk of listing a house on the real estate industry's Multiple Listing Service for an excessive amount.

The updated Zillow site now includes a wiki with over 100 articles about real estate by Zillow editors and, eventually, users of the site that choose to contribute. The company says it has also upgraded its map and search functionality.

Zillow launched in February 2006.