It is amazing the resources that you can find on the Internet. One of the best I have found is a full length Master’s level course on apologetics from Reformed Theological Seminary in MP3 format taught by John Frame. It is twenty-seven lectures and gives a great overview of the philosophical issues as well as the history of apologetics from Justin Martyr to the present. I have not finished listening to the entire course yet but I am thoroughly enjoying it. You can find the course on iTunes here.