http://sketchup.google.com/product_suf.html

SketchUp is a simple but powerful tool for quickly and easily creating, viewing and modifying your 3D ideas.

- Click on a shape and push or pull it to create your desired 3D geometry.
- Experiment with color and texture directly on your model.
- Real-time shadow casting lets you see exactly where the sun falls as you model.
- Select from thousands of pre-drawn components to save time drawing.

Google SketchUp (free) is an easy-to-learn 3D modeling program that enables you to explore the world in 3D. With just a few simple tools, you can create 3D models of houses, sheds, decks, home additions, woodworking projects - even space ships. And once you've built your models, you can place them in Google Earth, post them to the 3D Warehouse, or print hard copies.

Google SketchUp is free for personal use. No registration is required.