TagSpaces is an offline, open source, document manager with tagging
Freeplane add-on for task management and memo taking
Set styles to words and create a Table of Contents in a click
An example of how to use the Tilia packages to create great content
Plain-text file notepad with markdown support and ownCloud integration
Open Source Enterprise Content Management ECM
Real-time collaborative writing
Piggydb helps you have more fun with knowledge creation.