Those interested in apologetics are most likely familiar with Biola University and their Masters Program in Christian Apologetics. With that in mind, it is possible to find great audio resources in their chapel archives, which can be browsed on the Biola website or automatically found in iTunesU here. Some audio of interest includes:
• Understanding Intelligent Design : Sean McDowell
• Was Jesus an Advocate of Blind Faith? : Craig Hazen
• Will Heaven Be Worth It? : Clay Jones
• On Suffering & Following Jesus : Steve Porter
Also check out the Defending the Faith channel in iTunesU, which includes video of some of these lectures as well.