The Ruby on Rails web framework. There are a lot of issues being tracked in github leading up to the 4.0 release.
Open Source multi-language/multi-currency/multi-store eCommerce platform
The Rails application that powers OpenStreetMap
🍻 A CLI workflow for the administration of macOS applications distributed as binaries
A pure Ruby code highlighter that is compatible with Pygments
A platform for community discussion. Free, open, simple.
:gem: A fast, open source text processor and publishing toolchain, written in Ruby, for converting AsciiDoc content to HTML 5, DocBook 5, and other formats.
Git repository of MarkUs
Classy web-development dressed in a DSL (official / canonical repo)
Simple, efficient background processing for Ruby
Server automation framework and application
A simple, Git-powered wiki with a sweet API and local frontend.
A Ruby gem for communicating with the Twilio API and generating TwiML
Vagrant is a tool for building and distributing development environments.
Metasploit Framework
Raven is a Ruby client for Sentry, an-open source error reporting service (getsentry.com)