On Writing by Stephen King is the absolute best. Part memoir, part master class, this book is one of the greatest things I've read, period. In addition to the basic elements of craft and technique, King also offers a crash course on grammar. King's book serves as excellent inspiration and motivation as well. Every writer should read this book.
Anne Lamott's Bird by Bird is a step-by-step guide on how to write and how to manage the writer’s life, based on personal experience. She shares what it takes to be a writer with a unique voice that is both honest and funny.
The Elements of Style by William Strunk, Jr. is the most indispensable writing resources on the market to date. Strunk's best advice is to "Omit Needless Words," but there are plenty other topics addressed inside the book. Overall, this book offers guidelines for effective and convincing writing.
Zen in the Art of Writing by the late Ray Bradbury is guaranteed to make you think about what it's like to write for a living. In addition to offering practical tips, Bradbury also celebrates the act of writing. According to him the success of a write depends mostly on how well the writer knows his or her own life. This book is definitely worth sitting down with.
These books will not only entertain you, but also improve your capability as a writer. If you haven't read any of them, do it right now. You'll be thrilled that you did.
What do you think? What books did I miss?