I used it for creative writing. While I used LaTeX for the text, I heavily used TikZ: the "mindmap" library for drawing mindmaps, the "chains" library for story lines, the "trees" library for relations and connections of fictional characters, matrices for easy positiong, arrows for connecting. And a very good point was: I could use the same macros in the conceptional drawings as in the text, regarding macros for names for example which still could change, and so staying consistent.