If you are interested in earning a certificate that offers courses in Church History, Old Testament, New Testament, Theology, World Missions and Biblical Interpretation then the Ockenga Institute of Gordon-Conwell Theological Seminary's Dimensions of the Faith Certificate program is for you. Also, it is absolutely free and totally online. I have gone through this program myself and highly recommend it to anyone interested. If you wish to take only some of the courses and not necessarily go for the certificate that is an option. Enjoy!
Some free online courses are available through www.alison.com. ALISON stands for Advance Learning Integrative Systems ONline. They offer free courses if you are able to study on your own online in a wide variety of subjects. These are perfect for preparing you for an exam in a topic that you are weak in or in need of a refresher course. They also have courses and diploma programs for professional development.