The real estate search and subscription site Trulia confidentially filed to go public last month, according to DealBook, The New York Times micro-site, which reported on the now-public information last Friday. (According to new SEC rules, companies with annual gross revenue of less than $1 billion can file registration statements that do not have to be disclosed until 21 days before “the company’s roadshow to sell the new shares.”)Trulia has 21,544 paying subscribers as of June 30, 2012. The site offers three monthly subscription plans at $39.99/month, $99.99/month and $199.99 month. That means the site’s annual revenues from subscriptions could vary between $10 million and $51 million. For the record, Trulia disclosed that it has $28.9 million in revenues as of June 30th (no breakdown on subscription versus alternate revenue streams like advertising and one-off classified sales) and a net loss of $7.6 million.Trulia expects to raise $75 million through its initial stock offerings.Trulia now joins a handful of other subscription sites that have gone public, such as LinkedIn (LNKD); Pearson (PSO), owner of The Financial Times and other subscription services; IAC (IACI), owner of Match.com; Netflix (NFLX); and The McClatchy Company (MNI), owner of 30 daily newspapers and news sites in 15 states.Executives at other subscription and membership sites that are considering going public should note that most publicly traded subscription sites have hybrid revenue models, most commonly combining subscription and advertising sales. It’s also worth noting that the subscription site industry is a $15 billion dollar industry consisting mainly of very profitable privately held companies, as indicated by Subscription Site Insider‘s 2010 Benchmark Report.