Agile Web Development with Rails. Dave Thomas, David Heinemeier Hansson, et al. Pragmatic Bookshelf, 2005.
Ruby on Rails is a framework for developing web sites. This book explains it well. It starts with a decent-sized online store as a running demo (more than 100 pages of text go along with it). I was able to implement along with little trouble (also using a handy copy of Programming Ruby). The rest of the book is an exploration of key areas: persistence, controllers, views, and more. It closes off with information on deployment and scaling, giving you a sense of the options you have in this crucial stage. All in all, an excellent introduction. (Reviewed May, ’06)