Decentralized Services
Various open-source services meant to be instanced by anyone.
Mastodon
Decentralized twitter
MediaGoblin
Media publishing platform for video files and sound files
Etherpad
Real-time collaborative document editor
Wekan
Decentralized trello
Rocket.chat
Decentralized slack
Uses node.js so honestly just hosting an IRC might be a better idea
Sandstorm
Tries to simplify hosting of "webapps" by providing an interface to installing instances of various services, like Etherpad and MediaGoblin (and a guide for how to get it running on an Amazon EC2 instance)