You've probably already heard the term MOOC. These Mass Open Online Courses aim to connect online learners with classes crafted by the best in the field. Professors from schools such as Johns Hopkins, Emory, Harvard, and Stanford provide the materials (video/audio lecture, readings, tests, forums) and all you need is Internet access and a desire to learn.
MOOCs are typically free, typically participatory, and can be taken anywhere you can connect. There are many MOOC hubs such coursera.org, edX, and Khan Academy. Here are two articles that list even more.
I have personally used coursera.org and highly recommend it as a tool for continuing your public health education. Classes are available on a wide range of topics, useful to help you review what you learned in school or delve into the latest issues in public health. Most of the classes on this website are offered in sessions so you can participate in real time with professors and other learners. Courses are free, but you have the option of paying for certification awards.
For those of you involved in public health and nutrition, Public Health Online offers a resource page with links to several free MOOC nutrition courses. I recently took Nutrition for Health Promotion and Disease Prevention and it was extremely useful.
Join the forum to share a public health MOOC that has been helpful for you.
Check out Resources for MPHGrads to find other useful gems to help you make a difference in the world.