Getting the right hotel room—especially one with a great view—can really improve your travel experience. To that end, Room 77 is building the world's first hotel room database to show you the actual view from your room before you book.
There are many sites for finding and booking a hotel stay. Room 77, currently in beta, travelers virtually see the view from each room (or, well, a fabrication of it using Google Earth technology) and also find each room's location on interactive floor plans. If you really detest having a room near noisy elevators, for example, this service would be great for you.
There's room preference matching, room selection tips for each hotel (e.g., "river views are available on any floor"), and an iPhone app as well.
As a new service, though, Room 77 currently only features hotels in sixteen destinations, including London and major US cities. New destinations and hotels are promised every month, so the service is something to keep an eye on if your hotel room stay makes a big difference to you as a traveler.