I don't know of any free software - I use mindmanager which I got fairly cheap as a student (I bought v 6 when I did my MSc which I finished 5 years ago - it still works really well). You can get v8 from here for £60 http://www.studentexpressware.co.uk/gbu0-catshow/mindjet.html
Minmap integrates with Microsoft Office so I can plan a presentation or chapter using it and then export it to word or powerpoint as outline mode; not sure what the free ones can do.