[brandonmenc]

After reading the official guides (http://guides.rubyonrails.org) the next place to go is Railscasts (http://railscasts.com). Make sure you only watch the episodes for Rails version 3.2 and greater. Each episode is linked to a github project featuring complete Rails apps - read and modify those apps.

[josephlord]

The Hartl book others have mentioned is better than the guides if you need to know what todo not just how to do it (if you are new to web development rather than switching frameworks).

I'm also not sure about Railscasts for a beginner, the most suitable ones for a beginner may be pretty out of date now although there are probably a lot of useful ones still there.

[piratebroadcast]

GoRails.com has new railscast-style videos.

[netghost]

I have to second the official guides. They're mostly great.