Simulate multi-table inheritance for activerecord models using a polymorphic association

MySQL index hint support for ActiveRecord

Fast Rails serializer with built-in caching

Easy Parallel Executing using Celluloid

gem for adding DKIM signatures to email messages

Fluentd plugin to rewrite tags/values along with pattern matching and re-emit them.

https://github.com/tsukasaoishi/fresh_connection

Another business actions architecture for Rails apps

lazy_migrate lets you easily see which migrations have and have not been run, and makes it easy to up/down/migrate/rollback your migrations through a terminal UI. You can even bump migration versions in the event that you've just pulled master and somebody else merged their migration before yours.

Automatic detecting missing I18n translations tool.

A basic Mandrill delivery method for Rails.

Implements the common view pattern by which a list of messages are shown at the top, often a combination of flash messages and ActiveRecord validation issues on one or more models.

Improve perceived performance of your rails application with minimum effort

An extension to paper_trail, using this you can fetch actual object who was responsible for this change

Organize ActiveRecord model into a tree structure using PostgreSQL LTree

Debugging toolbar for Rack applications implemented as middleware. Based on logical-insight and rack-bug.

Properties gem for Ruby on Rails

A Rails engine that adds a piece of middleware to the top of your middleware stack that looks for redirect rules stored in your database and redirects you accordingly.

Resque plugin to add unique jobs

A nifty service layer for your Rails app