Well, if you google "raster to vector," you'll find a load of free and commercial apps. I'm guessing the quality will depend on the source material but I don't know. One you can try online is VectorMagic  vectormagic.com/home Ink9000 is a 3d oriented app that will create line art from .obj files inkulator.sourceforge.net/

You probably get more control by importing into something like Corel Draw or Illustrator and tracing manually. I haven't tried it but a free/inexpensive vector editor is DrawPlus www.freeserifsoftware.com/software/drawplus/

Other than that, I guess there's the line art filters in PhotoShop.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken