Bridgestreet.com recently integrated Virtual Earth into their site for locating corporate housing. The site allows you to adjust your search radius to locate housing around the world and visualize the property with aerial ortho and oblique (bird's eye) photography. I love this quote, "Our customers love our Web site! Using Microsoft Virtual Earth we can display our accommodations through a cutting-edge immersive online experience that’s revolutionary." All in all the site is very practical, but they could've added auto-refreshing data when panning/zooming (so, if I change my mind and want to searching in the US instead of Australia the map would change for me), but they didn't. Also, they could add much more data within the popup such as a photo of the property, bed/bath info, sq. footage and links to other pages (for booking a view or contacting an agent). Or, even better integrate virtual tours! But, they didn't. Still a great site, though.
Here's a link to the case study: http://www.microsoft.com/casestudies/casestudy.aspx?casestudyid=200896