When someone develops an interest in philosophy, good luck trying to keep them away from it. They'll find the stuff anywhere. These days, the internet makes possible such wide and instantaneous dissemination of philosophical materials that you literally can find it anywhere. (Take for example our list of 140 Free Philosophy Courses from Great Universities.) With developments in internet media, even the biggest institutional players in philosophy have joined in. The appearance of conveniently podcast lecture courses from the University of Oxford must count as an on-the-go philosophy fan's dream realized. Writing this very post while traveling through western Japan, I plan to soundtrack my journey with the John Locke Lectures, which rank "among the world's most distinguished lecture series in philosophy." (Then again, I do have a strong sense of incongruity.) The archive includes David Cooper's "Ancient Greek Philosophies as a Way of Life," David Chalmers' "Constructing the World," and Thomas Scanlon's "Being Realistic About Reasons."
But maybe you'd prefer to start from the beginning. Oxford offers philosophy podcasts on all levels, allowing you to gain a footing on the subject and climb upward. First listen to Marianne Talbot's "Philosophy for Beginners," which "will test you on some famous thought experiments and introduce you to some central philosophical issues and to the thoughts of some key philosophers." Then try the same lecturer's "Critical Reasoning for Beginners," followed by Peter Millican's "General Philosophy," an eight-week course geared toward first-year philosophy students. At that point, you're not far from the likes of "Nietzsche on Mind and Nature," "Kant's Critique of Pure Reason," and "Aesthetics and the Philosophy of Art," all of which you can absorb through headphones no matter where you're going or what you're doing. Whether or not you consider philosophy to be the most interesting branch of culture, it's certainly the most open.
All courses mentioned above appear in our collection of 1100 Free Courses Online.