Are there jQuery or JavaScript libraries or plugins for writing something like mind-mapping?
Try looking on this: http://www.headjump.de/article/arrows-and-boxes
It is jQuery library which transforms right syntax into mind-map-like graphs
More libraries you should like:
http://code.google.com/p/js-mindmap/
http://www.yworks.com/en/products_yfilesajax_about.html
http://www.kylescholz.com/blog/projects/jsviz/