Jerram Barrs has put a 26 lesson course on Christian apologetics on-line. The course, entitled Apologetics and Outreach is described as:
An analysis of the philosophical, religious, and scientific beliefs and ideas that have shaped different cultures and are now reshaping our multicultural and pluralistic society. Differences in attitudes toward the value and purpose of life, sexual identity and roles, racial and cultural differences, God, good and evil, superstition, etc., are all discussed with the goal of learning how to better communicate the Gospel in our society.
The course has sessions on Postmodernism, Missions and Apologetics. The course comes courtesy of the Covenant Theological Seminary, a Presbyterian Church in America seminary. Each lesson has a PDF of the lecture and a study guide.
Other courses available include Ancient and Medieval Church History, Biblical Theology and Christian Ethics.