Christian apologist John Warwick Montgomery has a number of good audio resources available, found here and here.
Testing the Truth Claims of Christianity
Part 1 | Part 2 | Part 3 | Part 4 | Part 5 | Part 6
• The New Atheists - MP3
• Responding to Bart Ehrman's "Misquoting Jesus" - MP3
• Answering the Objections of Unbelievers - Part 1 | Part 2
• Defending the Christian Faith in an Age of Relativism - MP3
Also added to the Ultimate Apologetics MP3 Audio Page.