How I Use It
I have used Google Earth in a class that involved intensive field studies. We used it to create a "fly over" of all of our study sites and helped students grasp scales and variations in habitats. It was also a great way for them to delve in to the geography and tree distribution on their sites. They could also see buildings, roads, and geographical features that may not have been easy to grasp on the ground and helped them think through possible ecological disturbances.
Google Earth provides such great visuals and has more functionality the more you work with it. Students are highly engaged and it is more a matter of keeping them focused than getting them excited. It doesn't require strong language skills, so it works great with ELL students.