I'm not aware of any GIMP plug-ins, but if you're starting with a photo or scan try using Inkscape or Delineate.
In Inkscape go to Paths > Trace Bitmap. You'll have to adjust the settings to taste. Then export it as a .png file using File > Export Bitmap.
Delineate will also require adjusting the settings to get the effect you want. It includes two programs, Potrace (which is what Inkscape's Trace Bitmap is based-on) and AutoTrace.
I'm not aware of any GIMP