Hi Campbell,
Good question !! I too had this question when I started writing the first edition of Getting started with Spring Framework.
I rely on Microsoft
Word for spell check
I do at the least two rounds of review of the book before I give it out to technical reviewers. Many a times the review time is almost 40%-50% of the time it took to write the book. I then ask a couple of my friends and contacts for reviewing the book. Once I receive review comments, I evaluate them and incorporate them in the book.
regards,