Ever since I've graduated college I've been looking for a way to keep my mind sharp. So recently I've began taking a few free online courses from EdX and Coursera. The latest one I just signed up for is called 'Central Challenges of American National Security, Strategy, and the Press', which is a course taught at Harvard by David Sanger and Graham Allison. Have any of you taken courses, whether online or at a college, post graduation?