Sure, everybody Googles, and Google Earth is de rigueur. But my question is, "Have you seen SketchUp [1]?" This tool for three-dimensional modeling is fun, engaging, and, in the end, powerful.
What I am enjoying the most about introducing SketchUp to kids and teachers I work with is the level of spontaneous creativity it engenders. Lots of kids, and more than a few adults, start doing cool things that require perseverance and complex thinking, and they are doing these things without being asked to. Need some help getting started? Free tutorials are available online, and the learning around this tool happens quite quickly.

Here are some ideas for classroom uses of SketchUp:

And what about an assignment for the teacher?
Like any good technology integration, make sure your use of SketchUp is not about the technology. You teach mathematics, English, science, world language, social studies, art, music, or some other curriculum area, so blend the use of this tool into your work -- set its quality and power to work for you and your students.
The kids will find the cool stuff and the open challenges in the weekly 3D Challenge [2], and they will discover that they can place their models [3] into Google Earth.
Teachers should head to the Education section [4], where they will find lots of ideas, a forum for discussion, and examples of student work from around the world.
Oh, and did I mention that professional architects use this tool? How about inviting professionals to school to either help you get started or, better yet, see the great things you and the kids are doing!
Let me know what you think about SketchUp and what you do with it, and, above all else, have fun!
Links:
[1] http://sketchup.google.com
[2] http://sketchup.google.com/3dwarehouse/cldetails?mid=6c7571cc33e0719d70eed953ff2880fe&scoring=p
[3] http://sketchup.google.com/support/bin/answer.py?hl=en&answer=36241
[4] http://sketchup.google.com/customers/education.html