Aidan Chopra, the author of Google SketchUp for Dummies has an entire series of accompanying videos on YouTube that help show you how to use SketchUp, Google’s free 3D drawing program. I’ve tried SketchUp, but found it unintuitive, and these videos (and I’m sure the book, too) truly help. The program has the potential to be invaluable to illustrators and cartoonists, as it allows you to quickly (and cheaply!) create models to work from — especially of different views of imaginary interiors.