ActiveWorkflow.org
turn complex requirements to workflows
alonetone
home for musicians, their tracks and albums
Bike Index
the internet's bike registry
Calls For Proposal App
manage a conference CFP
Discourse
next-generation discussion platform
Do Continuous Integration Yourself
open-source CI server
Errbit
open source, self-hosted error catcher
FeedBunch
simple and elegant reader
Huboard.com
better GitHub issues
huginn
open-source IFTTT
iNaturalist.org
social network for nature stuff
Juvia
commenting server of the likes of Discus or IntenseDebate
Open Build Service
build service for Linux packages
OpenProject
project management system
OpenSourceRails.org
the codebase to this site
Open Split Time
endurance event data management
Panoptes
API to support user-defined research projects
Podify
make podcasts from youtube-dl
Postal
mail delivery platform for incoming and outgoing e-mail
PublicLab.org
collaborative knowledge-exchange platform
Skyderby
flight analysis and competition scoring
TaxonWorks
workbench for biodiversity informatics
Texterify.com
translation and localization management
uk-postcodes
postcodes application
Verboice
Toolkit for people who literally "need a voice"