29 Lesson Preaching Course MP3 Audio by Bryan Chapell
Here is another great resource from Biblical Training: a 29 Lesson MP3 course on Preaching by Dr. Brian Chapell. (See also his book on the topic: Christ-Centered Preaching: Redeeming the Expository Sermon.) This course covers everything from getting started, constructing the parts of the sermon to illustrations, application, and a lot more. (Curriculum PDF here.) Original course link here.