adopt-a-hydrant
adopt-a-hydrant software
Annict.com
anime website
Brimir
an email helpdesk
Catarse
open-source crowdfunding platform
Coursemology
open-source gameified learning platform
Diaspora
community-run, distributed social-network
Discourse
next-generation discussion platform
Ekylibre
farm management information system
FeedBunch
simple and elegant reader
fromthepage.com
crowdsource handwritten documents
GitReports.com
allow anonymous users to submit bugs to GitHub repos
Helpy
A Modern Helpdesk Alternative
Hitobito
full-scale group hierarchy management
Hours
Time registration that doesn't suck.
icare
carpooling platform
Lale Help
collaborative platform for refugee support
Loomio
make decisions together
Mastodon
distributed, interconnected microblogging
openstreetmap.org
crowd-sourced map of the world
Pig CI
Rails performance monitoring, plus CI
Pokr
agile estimating and planning
PublicLab.org
collaborative knowledge-exchange platform
rubygems.org
The Ruby community's gem hosting service
Skyderby
flight analysis and competition scoring
TimeOverflow
time banking system
tip4commit.com
reward contributors
WikiEduDashboard
course dashboard system
World Cube Association
everything for the World Cube Association