Zillow.com surpassed Yahoo Real Estate to become the second most visited online real estate site during the month of March, according to a new report from Experian Hitwise. Zillow -- which for the past two months had ranked third -- recorded a search market share 3.49 percent. That compared to industry leader Realtor.com which came in at 6.51 percent. Yahoo Real Estate finished the month at 3.38 percent, while Rent.com came in fourth at 2.75 percent and ZipRealty finished fifth with 2.52 percent.

Zillow.com's key rival, San Francisco-based Trulia, finished sixth with a market share of 2.32 percent. And Redfin continues to climb the online real estate charts as it expands service into more markets.

The Seattle online real estate company moved up to 19th, from 20th in February and 21st in January.

Zillow.com -- the heavily-funded Seattle startup led by Rich Barton -- certainly has its eyes on becoming the biggest destination online for real estate information. And it has been adding several services in recent months, which expands its reach. (Most recently the mortgage marketplace, an iPad app and rental listings).

Interestingly, Experian Hitwise also ranks the top search terms in the category. Those are "realtor.com," "apartments for rent," "zillow," "real estate," "century 21" and "zillow.com."