Somehow or other I have come across a site that runs deep with promising-looking free audio – including studies of entire books – by such teachers as James Montgomery Boice, S. Lewis Johnson, Dan Duncan, etc. I don’t know much about the latter two, but Boice is top-notch. I’m downloading his series on “Two Cities, Two Loves” – which I’m sure all you Tim Keller fans should be familiar with.
Anyhow, here’s the page. I’ll put a link up on my Resources page as well for future reference.