Online there is:
http://guides.rubyonrails.org/http://railscasts.com/ (but many not free, but worth it)
https://peepcode.com/ (not free, but worth it)
Most of what you run into you'll be able to google but note that things changed significantly from Rails 2 to 3 (and a lot between 3 and 3.1), and changes between Ruby 1.8 and 1.9. Even though that is less of a pain than it used to be, it will probably trip you up here and there. Lots of stuff on blogs and that will bring up API documentation also. When looking for a gem google something you are looking for and github in same query, or look in
rubygems.org (search) sometimes.
This talk from Dave Thomas was great, even though several years old (large file):
http://scotland-on-rails.s3.amazonaws.com/2A04_DaveThomas-SOR.mp4If you have the luxury of quiet periodically in your car or wherever, check out the podcast at:
http://ruby5.envylabs.com/Also check out the hot stuff in GitHub:
https://github.com/languages/RubyKeep a listen on the core Rails list:
https://groups.google.com/forum/?fromgroups=#!forum/rubyonrails-coreand ruby etc on ruby forum:
http://www.ruby-forum.com/and stackoverflow, which is the best place to get questions answered.
While there are good choices on the book side of things, be careful; things get outdated quickly. And like I said, be aware that people are still using various older versions of Rails or Ruby, some may be using JRuby, etc.
Whatever you do, have fun!