Zillow.com filed for an IPO

Want to buy a stake in an unprofitable internet company?

Real estate site Zillow.com filed for a $51.75 million initial public offering Monday. ...

Zillow, founded in 2004, provides a database of more than 100 million U.S. homes for sale or rent, as well as homes not currently on the market.

In March, the site and mobile app together attracted 19.4 million unique users — a year-over-year gain of more than 90%.

Zillow's revenue has grown significantly over the past three years, according to the Securities and Exchange Commission filing. In 2010, Zillow's revenue jumped 74% to $30.5 million.

But the company has also booked net losses during that time, though those losses have been steadily narrowing. Zillow only lost $6.8 million last year, compared with $12.9 million in 2009 and $21.1 million in 2008.