I did just that with this first unplugged project. I created an extension assignment for students where they then take their work that they create on graph paper and then plug that into Processing. In essence the project "plugged in" is reconstituting the concepts that are broken down by unplugging it, learning them and being comfortable with them, then building it back up and plugging it back in. The currious kid who takes his dad's drill apart (me) to see how it works comes to mind, but then think about getting it back together and it working again (sorry Dad).
You can start finding examples of students plugged in work on our Open Processing gallery, check it out and comments are always welcome!!!