A lot of woodcuts, monochromatic printing techniques, and indeed old rasters are simply one color, and simulate value by varying the width of the lines that pass through the image. I was curious how this would look in a realtime 3D engine. Taking the original "control" image for reference:

I sampled the values of a given frame and varied their width based on the value of the given pixel. This is a single result:

The whole thing is vaguely reminiscent of the classic Sierra Online logo. The image itself is hard to read, but moving through the space is interesting - persistence of vision is a very important part of our senses when it comes to understanding spaces. I'll try to get some movie captures of the effect online.
Oh, and there's no reason it can't work in 3D:

This adds another element to the eyes when it comes to understanding the space, and creates some rather strange volumes.
The following shots are cheating a little bit - I added in the actual values of the sampled pixels. This makes a static screenshot a little easier to read, but kind of defeats the purpose of a true 1-bit, black and white image - it looks a little more like I'm blocking an image with lines instead of creating detail with them:

And in anaglyph 3D - in this push button age, why not?

I'll have to follow my own advice and post some movies - Non-Photoreal Rendering, if you have the goal of making it real time, needs to be seen in motion.