(If this question is not appropriate here, I am happy to be redirected.)
I teach mathematics at a small university having with extremely limited programming offerings. All of our majors take an introductory programming course (typically in Java), some of our mathematics courses integrate computer algebra systems (such as Mathematica), and lately I have been teaching a course in mathematical problem solving using Python (Sage, technically). Some of my students are quite taken with programming and spend quite a lot of time building their skills with fun challenges like Project Euler or Robocode.
Finally my question:
What sorts of certifications/credentials could a mathematics student pursue to demonstrate their programming knowledge to a wide range of potential employers?
All of my students have spent some time programming, and so could discuss their experience with an interviewer in good conscience. What I would like is some extracurricular certification of recognized value that the truly dedicated students could pursue to really set themselves apart from their peers as regards their programming skill.