I train for a marathon for about six months. Every year when I do this, I try to find something productive to listen to on my portable MP3 Player. This year, I took a college course on God's World Mission. It was free at Covenant Theological Seminary.
Here are some other courses that are available free online.
Ancient & Medieval Church History
Apologetics and Outreach
Christ-Centered Preaching: Preparation and Delivery of Sermons
Francis A. Schaeffer: The Early Years
Francis A. Schaeffer: The Later Years
God and His Word
Hebrews to Revelation
Humanity, Christ and Redemption
Life and Letters of Paul
Life and Teachings of Jesus
New Testament History and Theology
Old Testament History
Psalms & Wisdom Books
Reformation and Modern Church History
Spirit, Church, & Last Things
Now. Go learn something.