Crossway just released a superb book on preaching in honor of Kent Hughes:

Leland Ryken and Todd A. Wilson, eds. Preach the Word: Essays on Expository Preaching: In Honor of R. Kent Hughes. Wheaton: Crossway, 2007.

• See Crossway’s description of the book as well as its contents, introduction and chapter 1 as a PDF, and back cover.
• You can read the entire book online here.
• D. A. Carson‘s “Challenges for the Twenty-first-century Pulpit” (pp. 172–89) is exceptionally insightful.