When programming in the Ruby language, it is essential to know about the Enumerable module. The more Enumerable methods you know, the more concise and elegant your code will be. The Enumerable module is mixed into many common classes such as Array, Hash, and Range. It is also mixed into some not-so-common classes such as Set, Struct, and Enumerator.
The official documentation of Ruby 1.9.3's Enumerable module is good, but I don't like the alphabetical organization. I think you can understand what's going on better if you group the methods into similar categories. To that end, I have created a Ruby 1.9.3 Enumerable module quick reference. It's a one-page sheet that briefly documents ALL of enumerable's methods. Check it out!
Ruby 1.9.3 Enumerable module quick reference (PDF)
Ruby 1.9.3 Enumerable module quick reference (ODS)
Let me know if there are any errors or you think it could be better in some way!