The first book I read was Eat That Frog! : 21 great ways to stop procrastinating and get more done in less time / by Brian Tracy, a motivational writer and speaker.
The second book I read was The procrastinator's guide to getting things done / by Monica Romirez Basco. This approaches the topic from a completely different viewpoint. Basco is a psychologist specialising in cognitive behavioural therapy. So, unlike Eat That Frog, this book is all about why people procrastinate.