Lets you query activerecord using ruby code. Translates it to SQL.

Magic Multi-Connections allows you to write your models once, and use them for multiple database Rails databases at the same time. How? Using magical namespacing.

Here’s a trick when querying large result sets while being friendly to the computer

ScopedProxy uses with_scope and proxy objects to make it easy to find and count different types of records.

This plugin for ActiveRecord gives you the ability to define easy-to-use self-referential polymorphic associations with full array-like behavior (.push, .delete, <<) in your models.

CriteriaQuery is a plug-in for Ruby on Rails that extends ActiveRecord with a shedload of useful and logical methods so that you can chain together complex queries in an object-oriented manner.

Rubyisms in Rails Advent Calendar, starring ActiveSupport.