Yesterday, I was looking for some Google Earth overlays that I could use as a part of my lessons on WWI and WWII. In my search I came across two great lists of Google Earth files for these topics and other history topics. The first list came from a contributor to the Google Earth Hacks forum. The list is comprised of 199 Google Earth overlays featuring notable sites of WWI and WWII.
The second great list of Google Earth files for history teachers that I found is from Active History. Active History has 186 Google Earth files consisting of fly-over tours, 3D images, placemarks, and overlays. You can search the list by grade level, topic, time period, or file type.
Applications for Education
Google Earth is a great resource for providing geographic context for history lessons. Putting an overlay of a battle, building, or historical map provides greater geographical context than a standard textbook diagram provides. The files in the lists above could also serve as models for content that your students create in Google Earth.