The official Ruport book is now for sale on the Lulu website. If you’re looking to learn how to do ad-hoc reports in Ruby and add reports to your Rails application, this is a great reference and learning tool. (Disclaimer: I was a volunteer proofreader for the book.)
Still on the fence about buying it? There is a free HTML version available on the book’s website for you to preview and read, and 25% of the revenue from book sales will go to Engineering Without Borders. The book is also available under the Creative Commons Attribution-Share-Alike license.