Double Shot #1332

Rails 4.1.0: Spring, Variants, Enums, Mailer previews, secrets.yml - Yep, it's released. More than the particular features, I most like the smooth upgrade from 4.0 and the new determination to put out regular, solid releases.
Superhero.js - Resources for maintaining a large Javascript codebase.
RegExr 2.0 - Online tool for working with regular expressions.