I have found these to be quite helpful.
Apologetics Van Til, Bahnsen, Oliphint (iTunesU link)
History and Nature of Apologetics by Dr. Cornelius Van Til (iTunesU link)
Doctrine of God by Dr. Scott Oliphint (iTunesU link)
Christ and Human Thought by Dr. Cornelius Van Til (iTunesU link)
* These are all available from the Westminster Theological Seminary Resources website though you may need to create an account to download them.