Bluedoc
document management tool
brief-ideas
journal for brief ideas
CodeCuriosity.org
platform to reward OSS contributors
CodeTriage
directory of open-source projects with open issues
Danbooru
taggable image board
Discourse
next-generation discussion platform
exercism.io
code practice and mentorship
Fairmondo
free market place in the hand of the users
FleetYards
A Ship Database and Web API based on the official Star Citizen Ship Matrix
Huboard.com
better GitHub issues
Intercity
web-based Dokku deployment
Octobox
GitHub notification manager
Open Build Service
build service for Linux packages
openSNP
annotate your SNP-set
Pay
payments engine
Peatio
crypto currency exchange software
PublicLab.org
collaborative knowledge-exchange platform
Racing On Rails
bike racing association management
rubygems.org
The Ruby community's gem hosting service
samson
Web interface for deployments
Spina
A beautiful CMS for Rails developers
Tracks
software for implementing David Allen's Getting Things Done™ methodology
whitehall
government content publishing for gov.uk
Wreeto
note-taking, knowledge management, and wiki