Google has released an updated version of their Google Earth site. The new version has all the features that use to be in the paid for version.
The site is great. The images are good and the ability to change the angle is surprisingly effective -- especially given that we know the satellite only took its shots from one angle.
With the elections coming up, the political maps are particularly timely for social studies classes.
There is a lot here. Give it a try and try stop using it. It's addictive.