For the past several years I have been using a program called SketchUp to help me pre-visualize projects I need to conceptualize. SketchUp allows me to very quickly mass together an environment, find a nice camera angle, and then print it out as an armature for my final drawing. What makes it the most powerful is that I can then hand a client a concept that is not only accurate, but to scale! Being confident that your designs are actually build-able is amazingly valuable, and with some clients I can even send them the rough SketchUp model as well. This truly does help blur the line between pure concept and production! I encourage you to check out SketchUp at www.sketchup.com, and take if for a spin.
To personalize my models even further, I have created my own hand drawn “rogues gallery” of scale people to populate my virtual environments.
To see an animated version of the above example, check out the "Concept" section of my website, www.doncarsoncreative.com