I do a ton of flying for business these days and one of my favorite travel search sites is Kayak.com (Farecast is another great search tool too). The idea was pretty simple - Kayak took a look at a crowded category on the Internet (travel sites) and told themselves they could do it better.

Roost.com, which launches today into public beta, is trying to do the same thing to real estate search. Coincidentally, the major investors in Roost (they received around $5 million in VC dollars to build the site) are the same folks behind Kayak.

So what does Roost think it can do better?

First and foremost – it’s fast. Blazing fast. The search experience is, quite frankly, awesome. Adjust a slider in a market and the property results update immediately through some slick AJAX. To attain this speed, properties are displayed in a standard hierarchal list. A map view is also available, but it been pushed to a secondary tab - and I actually don’t really miss it.

Additional photos of any property are viewed inline and through some more slick AJAX, can appear and disappear with the click of a button. Rollover any thumbnail and you get a popup of the larger image.

Secondly, it’s complete. My biggest issue with the other Real Estate 2.0 sites is their incompleteness. Don’t get me wrong, they’re great sites; but the bottom line is that Zillow and Trulia don’t have all the listings and until they do, I just can’t recommend them as a tool for consumers or buyers. Period.

Roost, on the other hand, is not striving for national coverage. As CEO Alex Chang put it when I spoke with him last month, “We don’t want to launch nationally and be lame.”

Rather, Roost has cultivated partnerships with local MLS’ and brokers’ IDX feeds to provide complete coverage in each market it enters. It reminded me of the approach another of my favorite search tools, Estately.com, has taken.

Unlike Estately however – which only works in Washington State - at launch Roost will be live in 14 markets. These include Atlanta, Baltimore, Boise, Boston, Chicago, Dallas, Houston, Minneapolis, Orange County, Philadelphia, Portland, Sacramento/Modesto, Washington D.C. and San Diego. Chang expects by the end of 2008, they will be in close to 40 markets.

How it works is, in each market, the search results are sponsored by an individual broker (e.g. “Portland listings brought to you by…”). As a consumer, if you want more information on any particular listing, including contact information, all the traffic drives through to that sponsoring broker’s site.

Every market however, can have an unlimited number of sponsors and the sponsors rotate in based on the amount of traffic they have bought. This is perfect for some of the smaller brokerages that may not have many listings to market themselves (and therefore can’t participate in Z or T’s listings feeds) but are still looking to court buyers online.

Roost also offers those brokers a co-branded/private labeled search interface they can embed into their site too.

Personally, I really like the approach Roost is taking. (And as a buyer myself right now, especially thankful they chose to launch in Portland!) Like Estately, I think they may have very well nailed the right mix of best of breed search and having the total package when it comes to listings.

They have a bit of catch-up to play in terms of building their consumer traffic; Z and T have a good headstart - but just like Kayak, I think I may have just found a new favorite.