Journalism guru Roy Peter Clark is the author of one excellent book for writers, Writing Tools: 50 Essential Strategies for Every Writer. A free podcast summary of each tool can be found here.
I see Clark has a new book slated for release in mid August, The Glamour of Grammar: A Guide to the Magic and Mystery of Practical English. Looks fabulous.
Tony Reinke 
Tony,
What books have you found most helpful specifically for writing sermons? I’m thinking there’s probably a difference between writing that will be preached and writing that will be read. Maybe you’d say reading sermons is most helpful in learning to write them.
Any thoughts?