I just listened to “Preaching Christ in a Postmodern World,” a D.Min. course that Tim Keller and Ed Clowney co-taught at RTS about a decade ago. It’s 22.4 hours long, and it’s stimulating, especially the Q&A and the lectures by Keller.
Related: “Tim Keller: Preaching to the Heart“
Last May I listened to seven short sermons by Tim Keller on Luke 15 that convey the message of this book:
Timothy Keller. The Prodigal God: Recovering the Heart of the Christian Faith. New York: Dutton, 2008. 
This weekend I read the book and watched the corresponding DVD. The main feature of the DVD is Keller’s creative 40-minute readers-theater-style summary of the book. Both the book and DVD are first-class. And convicting.
Update: Cf. my brief review.
“The difference between a solid church and a terrible church is pretty much up to you. The difference between a solid church and incredible success has almost nothing to do with you at all. It’s like you are out there paddling on your surfboard, and suddenly the wave comes and you ride in, standing up like you’re a Greek god. That has everything to do with the wave.”
–Tim Keller, quoted in Tim Stafford, “How Tim Keller Found Manhattan,” Christianity Today cover story
I just listened to seven short sermons by Tim Keller on Luke 15, which convey the message of his book The Prodigal God: Recovering the Heart of the Christian Faith (audio). Thoughtful. Stimulating. Convicting.
The first sermon is from Sept. 2005, and the latter six are from fall 2008:
Update: Cf. my brief review.
On October 19, 2008, Tim Keller presented two lectures at Oak Hill College on “Preaching to the Heart”:
Here’s how Oak Hill College describes them:
Jonathan Edwards believed that the ultimate purpose of preaching is not only to make the truth clear, but also to make it real—affecting and life-changing. This is usually covered under the topic of “application”, though framing the subject in that way often results in a “tack-on” of practical advice after a dry, academic exposition.
How can we preach the text from first to last in a way that exalts Christ, changes heart motivations, produces wisdom and wonder, persuades the sceptical and results in real life change? In his two lectures, Tim Keller explores these challenges to the preacher.