natto provides a naturally Ruby-esque interface to MeCab. It runs on both CRuby (mri/yarv) and JRuby (jvm). It works with MeCab installations on Windows, Unix/Linux, and OS X. No compiler is necessary, as natto is not a C extension.

Nested scaffold generator for Rails

Pippi is a utility for locating suboptimal Ruby class API usage.

Rubygems plugin system using Gem.find_files, $LOAD_PATH and $LOADED_FEATURES.

Helps to save your eyes, when reading hardcore SQL requests in console

Prawn/QRCode simplifies the generation and rendering of QRCodes in Prawn PDF documents.

A web interface for the que queue

If the user clicked through from an affiliated site, this middleware will track affiliate tag, referring url and time.

rails-latex is a renderer for rails which allows tex files with erb to be turned into an inline pdf.

Simple gem to translate routes in Rails 3.x based on translate_routes

Scan for definitions and references in your Ruby code.

Open local or remote XLSX, XLS, ODS, CSV (comma separated), TSV (tab separated), other delimited, fixed-width files, and Google Docs. Returns an enumerator of Arrays or Hashes, depending on whether there are headers.

RequestLocals gives you per-request global storage in Rails

Tracks jobs performed, failed, and the duration of the last 100 jobs for each job type.

Run RuboCop against your Markdown files to make sure that code examples follow style guidelines.

Implementation of basic 2D geometry algorithms in Ruby

maven support for ruby DSL pom files. MRI needs java/javac installed.

Use Valgrind memcheck without going crazy

A simple client library to remotely access the Sailthru REST API.

MySQL adapter for thoughtbot/scenic