Some very kind people have told me that Objects on Rails is worth more than the $5 I'm charging for the downloadable version. If you are one of the people who feel this way, and you'd like to make an extra contribution to support my blogging, screencasting, podcasting, public speaking, and writing efforts, this package is for you. Along with my gratitude and everything listed in the regular download edition, you get:
A "developer's notebook" documenting some guidelines, techniques, and ideas for applying classic object-oriented thought to Ruby on Rails applications. This book is aimed at current Rails developers looking to grow and evolve Rails projects while keeping them flexible, maintainable, and robust.
You can also read the entire book online.