I spent some time exploring the Google Educator Tool SketchUp and I think it is pretty amazing. I can see immediate uses in my dyad geometry class. Have you ever tried to draw a circle in front of a class of 8th graders? There are a series of tutorials I watched before trying out the tool for a test drive. Here is the one of the tutorials on circles to give you an idea of how easy SketchUp is to use.
I explored SketchUp using the free version that I downloaded. There is also a professional version that is available and I asked my engineer husband if any of the CAD folks in his office used the tool. He tells me that the software they typically use is pretty expensive and specific to their needs. He was blown away when I showed him a couple of the tutorials on how to use the tool for designing buildings and bridges.