Google is once again making waves about its intentions in online real estate, with an executive of the search giant reportedly saying at a conference last week that they are "actively looking to acquire one to two small real estate companies a month.”

Yes, you read that right: one to two companies a month. Whoa... That would be quite a buying spree.

It is unclear what Google's Sam Sebastian meant by "small" acquisitions since that word can take on various definitions for a company with a market value of $184 billion.

Nonetheless, it appears that Google will be on the prowl in 2010. And that will likely mean a trip or two to Seattle, the hotbed of the online real estate industry. [Editor's Note: We are hearing that the initial report may have misquoted Sebastian, and that he actually said that Google plans to buy one to two companies per month across various industries. That follows similar statements by other Google executives.]

Google has already been rumored to be interested in San Francisco-based Trulia, perhaps the most likely of candidates. But there are other online real estate companies that might grab Google's attention. Here's a look at five Seattle online real estate companies, with a short analysis of whether they make sense to be added to the Google arsenal.

ActiveRain: The Bellevue company is a bit of a wild card in terms of an M&A candidate for Google. ActiveRain operates a free social network for real estate agents, an audience that Google would want to tap. But would buying ActiveRain really give them their connections? If Google's goal is to help consumers more quickly and easily buy and sell homes, I am not sure how ActiveRain would help them achieve that goal.

Estately: Estately would meet any definition of a small company. And co-founder Galen Ward has certainly built an impressive online real estate site at a fraction of the costs of his competitors. But Ward probably didn't make many friends with Google after he penned a guest post for TechFlash five months ago in which he was highly critical of the search giant. In the post -- titled "New Google is the old Microsoft" -- Ward said that Google uses its search engine muscle to "promote their often inferior services." Perhaps Google would like that candor. Or, maybe not. Nonetheless, Estately's map-based search has received kudos from real estate bloggers who consider it among the best.

Market Leader: It is unclear what Google's intentions are in online real estate. Do they want to buy traffic (eyeballs) or tools (technology)? If the company really is looking to gobble up one to two companies per month, than it probably will do both. Market Leader -- the publicly-traded company formerly known as HouseValues -- provides marketing and advertising services to real estate agents. It is primarily a lead generation service for real estate agents, a business that Google may or may not want to get into. Founded in 1999, the business has been undergoing a radical transformation in the past year. And given the restructuring and repositioning, the price now might be right. The market value of the company now stands at $48.5 million, and Market Leader posted cash and cash equivalents of $53 million at the end of the third quarter. Buying Market Leader could be an easy way for Google to gather some expertise in the real estate sector from people who've been in the business for more than a decade. The company -- which became an authorized Google reseller in 2008 -- listed Google as a competitor in its most recent annual report.

Redfin: Does Google want to become a real estate broker, employing agents in cities around the country? Probably not. And because of that, it's unlikely that Google would buy Redfin. Still, the Seattle startup has some interesting aspects that could make it attractive to the search titan. For one, Redfin made a high-profile switch from Microsoft Virtual Earth to Google Maps in December 2008. It is also worth noting that Redfin founder Glenn Kelman previously worked at two Sequoia-backed technology companies. (Sequoia was an early backer of Google). From what we're hearing, Redfin's mobile application is among the best. So that could become an attractive asset for Google as more consumers search for homes while on the go. And -- even though Google may not want real estate agents spread from Atlanta to LA -- it may find Redfin's relationships with various Multiple Listing Services attractive. Other online real estate companies don't have those ties.

Zillow.com: The Seattle online real estate company certainly has built one of the most recognizable brands in the online real estate category. And Google could make a serious statement by going after Zillow, the third biggest online real estate site in the country. But I'd be surprised to see it happen, especially if the search giant plans to get into the business through a series of tiny acquisitions. A Zillow purchase would be anything but small, with reports that the startup's last financing round valued the company somewhere in the neighborhood of $400 million. (Zillow has raised $87 million, so venture backers would want to see an exit in the $1 billion range to really be satisfied). Furthermore, Zillow CEO Rich Barton doesn't want to sell out. He's already built one major Internet brand, Expedia, and everything points to the fact that he's looking to do something similar with Zillow. There's also been recent chatter from Zillow execs about the possibility of an IPO next year.

There's certainly a number of other online real estate companies that Google could go after outside of the Seattle area, and Greg Sterling offers his own analysis in this post. Roost.com, Redfin and HotPads are all possible candidates, with Sterling offering Roost as his number one choice.

"My guess is that Google will buy sites that offer rich functionality, have established relationships with MLS services, are already established marketing platforms for brokers/agents and/or have relatively comprehensive hooks into rental listings," he writes.

Interestingly, in some ways, that describes all of the companies above. However, I don't see a natural takeover candidate from the five companies mentioned above. I guess we'll have to wait and see. So, stay tuned to see where Google goes in online real estate.