“WordPress 3 Complete” book written by April Hodge Silver is a excellent guide to kickstart, tweak and to play with your wordpress blog. This books comprises of 11 chapters which covers from installing wordpress to writing your own plugin (This book author recommends some programming knowledge in PHP, HTML and CSS).
Each chapter is explained with screenshot, examples, code snippet and reference if you want to learn a particular topic in detail. I would recommend this book to everyone who are new to wordpress and wants to customize your blog with custom themes and plugin.
You can buy this book from the following store