I wrote a smaller version a few months ago with the same modules at gaweda.tumblr.com. I sent the writer some questions about his purpose as well.

I'm attempting to re-implement Viola Jones without OpenCV as a way to really understand what is going on in the algorithm (a little more difficult than I imagined). Eventually developing a feature extractor.

One of the bigger issues I find myself asking is how can I turn face detection into a business model? Everything I imagine only seems to point to mobile apps, but I can't imagine that can replace a full-time job.

I could branch into recognition, but there a plenty of companies that already have that developed.