counter_cache, but much more powerful

A CMS engine for Ruby On Rails projects using mongodb. Featuring customizable page types, url nodes and more

This extension provides contiguous positionning capabilities to your ActiveRecord models.

Postablr a mountable blog engine similar with focus on tumblr entries style

Adds a preload_pluck method to ActiveRecord that allows querying using Rails 4 preload-style eager loading, and return a 2-dimensional array without ActiveRecord model creation overhead.

Prestashop WebService API library

Price history with easy.

This simple gem will help you with keeping default or primary record (one record that is marked as primary) - ie. default domain or language for site

An easy, and extensible transactional event notification add on for Spree.

This gem should support you when using rails scaffold (or a lot of simple CRUD models/views/controllers) in a programmable fashion, removing repeated code when possible and making it configurable

Promonizr is a gem to connect with API REST of promotions

Protected is a gem for rails that gives you user authorization, administration, auditing in a mountable Engine

A command line utility which connects to a Panasonic PABX via *telnet* and retrieve calling information. Filters valuable content while keeping the original fixed-space format.

Official Qiita:Team Services Integration

An orm for the cassinatra rest interface.

Qubell API wrapper

Quiver is a framework for writing web APIs

Ruby wrapper for BloomNet Center's API

r2d3 is in development phase, watch this space.

High level classes (consumers, producers, publishers...) for a Ruby application to use RabbitMQ.