Refactoring Workbook, William Wake. Addison-Wesley, 2003.
[Consider this a summary rather than a review my own book.] My goals were to create a workbook that helps people practice recognizing smells (problems) and learn to apply important refactoring techniques. There's a "smell finder" inside the covers to help lead you from symptoms to solutions. The table of contents and the book's home page are here.
(April, '06)
(April, '06)