Illustrate! by David Gould is a non-photo realistic renderer. It allows you to render your 3D scene in a variety of artistic styles, such a cel shading style, a technical illustration "hidden lines" style and more.
I've used this renderer before to export vector animations to Adobe Flash and it worked brilliantly. You can also export to Adobe Illustrator and Autocad DXF files.
More info at David Gould's site here
Here is a video tutorial from www.designreform.net showing how to use Illustrate! (Tutorial)