By David A. Black; Manning Publications, 2006, ISBN 1932394699. Shows what one is doing when writing Rails Web applications, and how Ruby methods expand limits of what can be done in Rails.

By Dave Thomas, David Heinemeier Hansson, Leon Breedt, Mike Clark, James Duncan Davidson, Justin Gehtland, Andreas Schwarz; The Pragmatic Bookshelf, 2006, ISBN 9780977616633. First definitive guide to developing with Rails; Jolt-award winner.

Official site. Code updates, free: introduction; chapter 2, 5, 6 screencasts; chapter 15 download. Link to Safari Books download. Free copy for non-profit work.

By Michael Hartl, Aurelius Prochazka; Addison-Wesley Professional, 2007, ISBN 9780321480798. Shows how to build large projects with RoR by developing real application step by step, from basics to a highly dynamic site.

By Obie Fernandez; Addison-Wesley Professional, 2007, ISBN 9780321445612. Comprehensive, authoritative experts guide to building production-quality software; shows full API, Ruby idioms, design approaches, libraries, plug-ins.

By Rob Orsini; O'Reilly Media, 2007, ISBN 9780596527310. From basics (install Rails, set up development environment), to latest techniques (developing RESTful web services). Each recipe has tested solution, treatment of how and why it works.

By Barry Burd; Wiley Publishing, 2007, ISBN 9780470081204. Introduction to build Web and database applications fast via Ruby scripting language and Rails framework.