This is a good resource: <a href="http://railsapi.com/" rel="nofollow">http://railsapi.com/</a><p>And this has docs for many different versions of Rails: <a href="http://railsbrain.com/" rel="nofollow">http://railsbrain.com/</a>
Or run to terminal, do "gem server", visit <a href="http://localhost:8808/" rel="nofollow">http://localhost:8808/</a> and check out the built-in RDocs for all the Rails-related gems (and all the other ones installed).