Typography is the craft of endowing human language with a durable visual form, and thus with an independent existence. (...) Typography remains a source of true delight, true knowledge, true surprise.

Robert Bringhurst, The Elements of Typographic Style

is “The Rails Way” by Obie Fernandez. Trying to learn RoR in my spare time over the past 12 months, I have to say that it is a lot of fun and easy to learn (as the frameworks advocates say) and that it can be hard for beginners sometimes, as the critics claim. This is the most readable reference book I have seen so far, it covers Rails 2 and on several occasions I was able to solve problems by looking them up in the book. Money well spent, probably too much details for the absolute beginner.