Alternative Augeas-based providers for Puppet,

Ronin is a Ruby platform for exploit development and security research. Ronin allows for the rapid development and distribution of code, exploits or payloads over many common Source-Code-Management (SCM) systems.

An IRC Bot Building Framework,

Boxroom is a web app that aims to be a simple interface for managing and sharing files in a web browser. It lets users create folders and upload, download and share files. Admins can manage users, groups and permissions.

UNIX Manual Page Editor with Ruby & GTK,

The core components of Ruby on Android,

Simple authentication for Ruby web apps, with Shoulda and Factory Girl tests for its test suite.

Ruby gem.

Sprockets: Rack-based asset packaging

Sprockets is a Ruby library for compiling and serving web assets. It features declarative dependency management for JavaScript and CSS assets, as well as a powerful preprocessor pipeline that allows you to write assets in languages like CoffeeScript, Sass, SCSS and LESS....

A ruby on rails engine which provides a very basic web application to use with other ruby on rails applications

A pure and simple Ruby client wrapper for the Twitter REST API.

To install Ruby Gem, at the command line type:
sudo gem install twitter4r