Google Earth is a 3d modeling program based on pictures of the entire surface of the Earth taken by satellites.  The geography class implications are obvious.  I'm a big fan of using mystery to teach.  Sometimes kids like the stuff we don't know better than the stuff we do.  Here is an example of someone using Google Earth to highlight some of the geoglyphs that can be found.

Here is a tutorial of Google Earth by a teacher.

Google Earth to teach area and perimeter.  Cool!

An example of teacher using Google Earth

Teaching students about the moon landings?  Try Google Moon

Teaching students about Mars?  Try Google Mars