I've been in sponge mode for a little while now trying to absorb as much information about Ruby and Ruby on Rails as possible. The great thing about an open source platform like RoR, is that there is an abundance of information available online. I know both Ruby and RoR are getting more and more popular, so I though I would share a few of the resources I have found useful.
First up, is Michael Hartl's Ruby on Rails Tutorial. This has to be hands down, the single most useful and helpful Rails guide anywhere. I plan to buy the book as well, even though the material is the same as the online tutorial, I like books, they make me feel smarter, and I really want to support the author of this great tutorial. Simply put, if you are interested in Rails programming, and don't follow any other link on this post, check this one out (or better yet, support Michael by buying the book!). Michael gives solid code examples, and teaches you to not only code an application, but code tests for the application as well, following the Red, Green, Refactor paradigm of Test Driven Development. You will develop solid habits here.
Next up, is TryRuby.org. This is a great little site that runs you through a nice little tutorial around the Ruby language using a browser based Ruby console. Although if you want to be a Rails developer you need to know Rails along with Ruby, it doesn't hurt to have as strong of a background in the Ruby language as possible. A few other Ruby resources are the Ruby Programming Wikibook and the Ruby User's Guide. These guides and others are linked from the documentation page on ruby-lang.org. One that I would like to mention specifically is Why's (Poignant) Guide to Ruby which is the single most enjoyable piece of technical documentation I have ever read. Another great interactive Ruby guide is RubyMonk, and I wanted to include it here since it's not on ruby-lang.org's Documentation page at this time.
A few more Rails specific resources are, of course, the Rails Wiki, The Meshplex Ruby and Ruby on Rails Tutorials and Rails for Zombies which is availible free from codeschool.com.
Also, no arsenal of online Rails information would be complete without a bookmark to railscast.com's Ruby on Rails Screencasts. These screencasts are searchable, and can help you find answers to many programming problems, and can help you overcome "coders block" when looking for ways to create an efficient solution.
Good luck to everyone on the journey of learning Ruby and Ruby on Rails, and I hope this little collection of links helps you as much as they have helped me. Obviously I haven't completed all of the tutorials (except Michael Hartl's), nor have I read through all of the documentation sites, but I continue to work toward expanding my knowledge nearly every night.