Room 77 shows you a list of rooms that match your preferences, with Google-generated views out the windows.

When checking in to a hotel, the old advice goes, see the room before you accept it. Don't like it Sniff dismissively at the bellhop, and talk your way into a better room.

Who has time for this Start-up Room 77, launching at the Launch Conference, is building a system that gives hotel guests a look at their potential room before they check in.

In a nutshell, the company is building a database of individual hotel rooms, including for each information like distance from elevators, what floor they're on, subjective ratings from people who have stayed in them, and--the sexy feature--a Google Maps image, with 3D buildings, of the view out the window.

If you get the upcoming Room 77 smartphone app, when you're checking in to a hotel you'll be able see if the room you're offered matches what you like, and also check out the view. Bad-for-you rooms will come back red-tagged. You can request another before you leave the desk.

Better yet, when you're booking a hotel room online, you can tell Room 77 what's important to you and it will rank the rooms in the hotel based on your preferences. You can jump between entries and see their views, and possibly interior pictures. It's very cool, just the thing for the control-freak traveler.

The mobile app will let you know if the room you&39've been assigned is a match with your preferences.

The thing is, though, there's no programmatic way yet to request a given room. Category of room, yes. Room number, no. Most hotels don't assign actual rooms until 24 to 48 hours before check-in. Guests sometimes request a given room in a booking, but in the global network of hotel services--hotel sites, travel booking sites, and trip planners--there's no standard way to pass room number requests through to hotels. If Room 77 is to really succeed, booking systems need to get finer-grained, so they can work with this data.

Assuming for the moment that Room 77 can build a good database of hotel room information, using its own services as well as customer-provided images and reviews, the company's future hinges on how successful it can be in inserting this database into the travel economy.

The first way the company will make a buck is straightforward: From booking fees, just like any other travel site. If you book through the site, the company will get its cut. You have to call the hotel to make sure you get the room you want, though. Room 77 provides a cheat sheet for doing so.

In the future, Room 77 may offer a premium "room request guarantee" feature. The best way to get the room you want currently is to contact the hotel a day or two before you arrive, and make sure some human matches your request with the room you like, or one very much like it. That's a pain for travelers who may have booked their stay weeks before. Room 77 may offer a paid service where it will make the call for you. As time goes on, the company may start to make these requests automatically, but that will require a fair bit of backroom negotiating with booking software companies. (Negotiations with Starwood are underway.)

Eventually, though, Room 77's real value will be in bulk transactions around its database--in selling the room-specific data back to hotels or allowing other travel sites or hotel sites to use the Room 77 database through a paid API. If Room 77 ends up with a lock on this data, this is the killer business.

Projecting the economics of Room 77 out a bit, this service could have an impact on how hotel rooms are priced. With granular data available to travelers about each room, it stands to reason that pricing could get granular as well. Instead of just booking a deluxe room at a hotel, you'd book a room by view quality and proximity to elevator, if that's what matters to you. An algorithm could end up pricing hotel rooms by demand, similar to how airfares change frequently based on booking flow, availability, and other projections. I'll leave the implications for Priceline and other semiblind booking sites as an exercise for the reader.

Not all the Google views are clear.

Room 77 has a smallish number of hotels at launch, but it's expanding. Users with the smartphone app will be able to help by taking pictures, reviewing rooms, and sending in snaps of the emergency exit maps on their hotel room doors. The company uses those to fill out its database.

In my quick review of the prelaunch site, I found that the Google-generated views from hotels' upper floors were useful and illustrative, but that Google's images from low floors (with blocked views) were more muddy than useful, due to the mostly poor quality of the photographs of building facades that Google projects onto the 3D models in its map database. Also, the service doesn't have the information that matters the most to the geek traveler: Wi-Fi signal strength in the room. I asked my contact at the company if they could add that feature ASAP.

Room 77 is a useful, fun, and economically interesting start-up. A few turns of the development wheel as the product grows up and this travel company could become very important.