Envy Labs Rails 3 Cheat Sheets is another great cheat sheet to add to our Web Developers Cheat Sheets. Some of these sheets may be a review if you’ve already been working with Rails 3 for a few months now, but they’re great if you’re just now getting the hang of it or you want a good reference guide.

Source: http://blog.envylabs.com/2010/12/rails-3-cheat-sheets/