Definitely a book for you if you want to get more done in a limited amount of time, if you're a manager, or if you're a procrastinator.
The book is old, and the references to computers will make you laugh, but the principles still stand. His book has a lot of parallels with Allen's Getting Things Done, which only underscores the usefulness of the book.
The back has a nice listing of time wasters by category, with a list of causes for each and how to deal with it.
One of the best books that summarizes time management in a no nonsense way. GTD is even better, but I love the old-school stuff in here. It's easily applicable to emails etc anyway.