Here is an interesting application showing the last 50 flights in Google Earth sold by travel site lastminute.com (updated every minute of course!). Apparently there is a LastMinuteLabs site experimenting with different Google Earth applications. I think this is good marketing, but also fun to watch.
The LastMinuteLabs site also led me to a site called HolidayAutos which has put together some Google Earth illustrations of drives between popular destinations with placemarks for good tourist spots to visit. For example, look at the Florida Keys drive , or how about a drive from Italy to Monaco?
I really think the travel industry should look more seriously at how Google Earth can be used to help get people excited about travelling. There are so many tools available with GE to help provide useful information, and rich presentations to help people get a feel for what travel to destinations could be like.