Planning Poker - Open source implementation of planning poker game (collaborative online estimation/voting tool).
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Firepoker - Agile Planning Poker powered by Firebase and AngularJS
Anchor CMS - Free and lightweight blogging system
Taiga - Project management platform for agile developers & designers
Textpattern - Textpattern is an elegant content management system that is free, open source software.