I work for Spree Commerce, the most flexible eCommerce platform built with Ruby on Rails.
I'm writing a book called Debugging Ruby that walks through common mistakes that people can make in Ruby and Rails code.
I've written an advanced book about Rails that costs only $25.00. Multitenancy with Rails teaches you how to build a multi-tenant application with Rails. Buy it now.
I've also written Rails 3 in Action, 1st Edition. There's a Second Edition coming, too.
For way too much more info about me: http://ryanbigg.com/about-me/