Though not read by Augustine himself, his On Christian Doctrine is being offered as a free audio book by Christian Audio for the month of April, 2007. Normally over $20 for a download, it is free this month if you use coupon code APR2007. They pick a different free download each month and it can be viewed here.
Disclaimer: I don’t know these folks and I receive no moolah for this link. I just thought you may want to listen to a little Augustine while jogging tomorrow.