Dabble Writer - Writing software for novelists.
MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Novlr - Online word processor and organizer for novel writing.
TiddlyWiki - a non-linear personal web notebook
SHAXPIR - A modern cloud workspace for fiction writing & worldbuilding
Confluence - Confluence is content collaboration software that changes how modern teams work