Google recently acquired a company (@Last Software) that creates a 3D modeling software called SketchUp. The software comes in two versions available, free and professional (it sells for $495).
Google SketchUp (Free) is for personal use, and no registration is required. While the professional version is for designers with more powerful features, such as the ability to create interactive presentations, or print to high-resolution devices.
Google SketchUp (Free) is a very powerful and easy-to-learn 3D drawing program. You can draw buildings you may want to build, plan wood making projects, design models, and more... After you create your image, you can upload it to a special site for storing it or you can post it into Google Earth.
Update: If you want to see a video of the software in action, check out this from CNet.