"Why are all of the cool dot-com real estate plays -- Trulia, Zillow, Redfin, HotPads, and so on -- privately held," I asked three years ago.

I'm finally getting my wish on Zillow, but is it too late?

The company that disrupted the online real estate market by turning real estate into a social endeavor through convenient free access to ever-changing home price estimates is finally going public.

Zillow burst onto the scene five years ago, just as the real estate bubble was inflating to a sudsy yet unsustainable level.

Internet real estate portals were more valuable then than they are these days. Market Leader, ZipRealty, and Realtor.com parent Move (Nasdaq: MOVE) have all shed more than half of their value. On the commercial real estate side, leading online marketplace LoopNet (Nasdaq: LOOP) went public a few months after Zillow's debut on Valentine's Day in 2006. LoopNet is trading marginally above its $12 IPO price, but it's going for less than half of its 2007 all-time highs.

It's not just here. Investor interest has even cooled on China's frothy real estate market. China Real Estate Information (Nasdaq: CRIC) and leading agency E-House (NYSE: EJ) have surrendered roughly half of their 2009 highs.

As far as niche sentiment goes, Zillow's timing is terrible. The upside here is that it has made the most of the realty lull to actually grow its business.

Zillow generated just $10.6 million in revenue in 2008, when it finally got serious about monetizing its magnetic website. Annual revenue has nearly tripled to $30.5 million. Burdensome losses have narrowed sharply with every passing year, and Zillow actually squeezed out positive adjusted EBITDA last year.

The metrics get even more compelling on the engagement front. Zillow attracts 19.4 million unique users, a nearly fourfold pop from where it was in 2008. Zillow's popularity can be attributed to the smartphone revolution, where its a hot download across all thee major platforms. Zillow was used on a mobile device more than 8 million times last month.

The challenge for potential investors will be to visualize the upside. Zillow makes its money from brand advertising and by getting Realtors to pay up for premium subscriptions. How big can this market really be? Will the real estate market ever regain the speculative sizzle that finds folks continually checking on what their homes -- or their targeted dream homes -- are worth?

The best argument for buying into Zillow is that the company was able to grow briskly, even as the real estate market dried up. However, in a climate where search giants have sticky mapping features and where sites like Facebook and Foursquare have cashed in on check-ins, potential competitive threats are also closer than they were when Zillow was redefining the experience five years ago.

Which company would you like to go see public? Share your thoughts in the comment box below.

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Longtime Fool contributor Rick Munarriz isn't interested in selling his home, even if he recognizes that the once red-hot South Florida market is a ghost of its former glory. He does not own shares in any of the stocks mentioned in this story. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.