Here are some samples I tried combining Freestyle using a couple of random models from Yepsketch. There are obviously some problems with just slapping them in there and rendering with Freestyle, but I'm sure someone with more experience using Freestyle could get this to work nicely. I'm not that experienced with Blender myself. It might be interesting to play around with these some more using other techniques like the inking tutorial over at BlenderNPR.
Update: I realized some of the weird extra lines in the model on the left (I think that was a dishwasher...) may be due to the very old build of the Freestyle Blender branch I have... so these might actually turn out better with a more recent version... Sadly I don't have the time to sort out compiling a new copy today.
Update 2: Compiling a new Freestyle branch seems to have helped. I think I've got the settings for Freestyle messed up somehow... or the settings I need for the dishwasher and the settings for the curvy chair are going to need to be different... actually the crease angles on the chair probably need to be quite different actually.
With some further adjustments I was able to get both to render the way I wanted.
Update 3: Another object from yepsketch rendered using Blender and Freestyle.