Hi, here is a script I've been playing with for a while: the idea is to get some quick vector output from Blender to feed Inkscape. It is not meant to be a NPR solution -as Freestyle will be- but you can still do some basic tricks. And it is pretty useful for simple shapes and so... I also tried to add a few abstract and geometric stuff into the mix.
Script will export current viewport -think a screen capture application- to a SVG file. Works with meshes and curves. I suggest you to open the svg file in a browser -Opera is very fast- and use it as a viewer while you play with settings. SVG code can also be edited inside the browser.
the SVG vector files for the picture above: M1 - M2 - M3 - M4 - M5 - M6
A couple of tips:
- limit the amount of exported geometry to get a faster export, but also to get different looks...
- use viewport to frame the objects, you can go ortho mode or edit lens value, check distortions
- 'add to svg' allows to append shapes to your svg, something like a 'multiple exposure' :p
here some test done with a previous version of script on a model from project london: arizona
edit: added some help here