Over the past few years I have enjoyed listening to educational stuff. It really makes traffic and housework tolerable. I love The Teaching Company courses, my older kids and I have loved everything we have listened to. They do, of course, cost money (unless you can borrow them from a friend like I do, or check them out at the library, Hoover used to have a lot of them). The library also has lots of books on tape.
Podcasts provide a great FREE resource on almost any subject you can think of. My favorites are Ravi Zacharias and R.C. Sproul. You can search for these, and many other Bible teachers, on itunes. Pretty much any radio show now has a podcast.
Below are links to pages with many links to educational courses, as well as free audio books:
Covenant Theological Seminary
Westminster Shorter Catachism